Blue Dragon

Here is a list of the monsters, their locations, and a small amount of pertinent info, if necessary. Some of these creatures CAN BE MISSED, so be warned (see the addendum at the end of this guide for which ones):

Monster 001: Poo Snake: Ancient Ruins Caverns
Monster 002: Stone Poo Snake: Gul Mountains
Monster 003: Iron Poo Snake: Fight a Roball (075) in the Mecha Base or a Poo Snake (001) on the Southwestern Deserted Island
Monster 004: Copper Poo Snake: Ancient Prison - Moat, Southwestern Deserted Island
Monster 005: Platinum Poo Snake: Hard to find, but eventually appears on the Southwestern Deserted Island
Monster 006: Golden Poo Snake: Southern Deserted Island
Monster 007: Compost Poo Snake: Gul Highlands, Southwestern Deserted Island
Monster 008: Pungent Poo Snake: Fight a Shrike Cockatrice (120) in Mural Valley West, Southwestern Deserted Island
Monster 009: Zebra Poo Snake: Ancient Ruins Forest, Southwestern Deserted Island
Monster 010: Dark Poo Snake: Fight a Poo Snake (001) on the Southwestern Deserted Island or find in the Primitive Cube
Monster 011: Jumbo Poo: Appears in Ancient Ruins Caverns if you return there and open the Blue Barriers
Monster 012: Corrosive Poo: Ancient Ruins Caverns after you kill the Jumbo Poo (011)
Monster 013: King Poo: Ancient Ruins Caverns after you kill the Jumbo Poo (011) and Corrosive Poo (012)
Monster 014: Hermit Crab Poo: Undersea Caverns
Monster 015: Coconut Crab Poo: Randomly appears when you fight a Jelly Jolt (021) party in the Sea Cube
Monster 016: Ore Hermit: Gul Mountains
Monster 017: Rock Hermit Crab: Northern Lal Mountains
Monster 018: Magic Jellyfish: Undersea Caverns
Monster 019: Blazing Jelly: Pachess Town - Underground
Monster 020: Lazy Gummyfish: Underground River
Monster 021: Jelly Jolt: Sea Cube
Monster 022: Sonic Strike Fish: Wetlands
Monster 023: Flaying Fish: Underground River
Monster 024: Sharkfly: Mecha Base
Monster 025: Sonic Sharkfly: Mecha Base Upper
Monster 026: Cutlass Fish: Wetlands
Monster 027: Swashbuckler Fish: Underground River
Monster 028: Gaudy Cutlass Fish: Northern Giant Ice Fields
Monster 029: Broadsword Fish: Undersea Caverns
Monster 030: Armored Fish: Sea Cube
Monster 031: Ghost Crab: Wetlands
Monster 032: Ghost Crab Mimic: Gul Mountains
Monster 033: Goblin Crab: Pachess Town - Underground
Monster 034: Mountain Crab: Near Talta Village
Monster 035: Land Crab: Coastal Road
Monster 036: Machine Gun Crab: Found ONLY in appears in the Flying Fortress. Randomly appears when you fight a Double Axe (217) party.
Monster 037: Bomber Mecha Crab: Mecha Base
Monster 038: Scavenger Wolf Ghost: Eastern Lot Wilderness, Western Lot Wilderness
Monster 039: Flame Wolf Ghost: Ancient Hospital Ruins
Monster 040: Snow Wolf Ghost: Ancient Hospital Ruins
Monster 041: Gale Wolf Ghost: This monster will not appear if you defeat the Rockwind Wolf Ghost (264) before it has a chance to split. Found in the Southern Lal Mountains
Monster 042: Stone Wolf Ghost: This monster will not appear if you defeat the Rockwind Wolf Ghost (264) before it has a chance to split. Found in the Southern Lal Mountains
Monster 043: Ancient Katydid: Near Mechat Crash Site
Monster 044: Glutton Locust: Jibral Plains
Monster 045: Ancient Cricket: Lago Village - South
Monster 046: Dulcet Katydid: Great Desert
Monster 047: Mist Walker: Gul Mountains
Monster 048: Poison Mist: Exile Forest Caverns
Monster 049: Slime Roamer: Forest of the Dead
Monster 050: Aqua Roamer: Sea Cube
Monster 051: Ancient Moth: Wetlands
Monster 052: Blazing Moth: Primitive Cube
Monster 053: Apocalypse Moth: Eastern Lot Wilderness, Western Lot Wilderness
Monster 054: Sleeper Moth: Near Devour Village
Monster 055: Hover Alarm: Ancient Hospital Ruins
Monster 056: Hover Patroller: This robot ONLY appears in the Flying Fortress.
Monster 057: Hover Claxon: Ancient Factory
Monster 058: Intercept Electrogue: Engage a Medic Maintenancer (060) in the Drill Machine or find in the Ancient Hospital Ruins
Monster 059: Intercept Dynadrone: This mecha is summoned by a Versatile Mecha Robo (073) in Nene’s Fortress, and will NEVER appear again if you destroy the Versatile Mecha Robo parties.
Monster 060: Medic Maintenancer: Drill Machine, Ancient Hospital Ruins.
Monster 061: Winking Medic: This mecha ONLY appears in the Flying Fortress and appears randomly when you fight a Flying Mecha Robo (069) or Double Axe (217) in the Flying Fortress
Monster 062: Coordinator: Ancient Factory
Monster 063: Squinting Cyborg: Mecha Base Upper
Monster 064: Smirking Scorpion: Lot Wilderness East
Monster 065: Paralyzing Scorpion: Gul Mountains
Monster 066: Tailgunner Robo-Scorpion: This creature randomly appears when you fight a Flying Mecha Robo (069) or Security Mecha Robo (170) party in the Flying Fortress in Nene's Fortress and ONLY appears there.
Monster 067: Shooter Scorpion: Jibral Highlands
Monster 068: Mecha Robo: Drill Machine, Flying Fortress, Ancient Factory
Monster 069: Flying Mecha Robo: Flying Fortress, Ancient Factory
Monster 070: Battle Mecha Robo: In the Ancient Factory, fight a Coordinator (062) and it may convert one of the Mecha Robos (068) it appears with into either a Battle Mecha Robo (070) or a Heavy Mecha Robo (072)
Monster 071: War Mecha Robo: Ancient Prison – Moat (Boss)
Monster 072: Heavy Mecha Robo: In the Ancient Factory, fight a Coordinator (062) and it may convert a Mecha Robo (068) it appears with into either a Battle Mecha Robos (070) or a Heavy Mecha Robo (072)
Monster 073: Versatile Mecha Robo: This mecha must summon Intercept Dynadrones (059). It appears ONLY in Nene's Fortress.
Monster 074: Gold Mecha Robo: Ancient Factory (Only found in the Ancient Factory on Disc 3)
Monster 075: Roball: Southern Giant Ice Fields
Monster 076: Thief Roball: Mecha Base Upper
Monster 077: Green Skeleton: Forest of the Dead
Monster 078: Purple Skeleton: Destroyed Talta Village
Monster 079: Red Skeleton: Pachess Town - Underground
Monster 080: Blue Skeleton: Devour Forest
Monster 081: Skeleton Captain: Destroyed Talta Village
Monster 082: Skeleton General: This creature is ONLY summoned by the boss Scything Skull-Spider (273) in Pachess Town - Underground
Monster 083: Servant Mecha Robo A: Nene's Fortress (Boss)
Monster 084: Enforcer Robot This mecha ONLY appears in Nene's Fortress.
Monster 085: Servant Mecha Robo B: Nene's Fortress (Boss)
Monster 086: Standard Defender: This mecha appears ONLY in Nene's Fortress.
Monster 087: Assassin Robot: This mecha appears ONLY in Nene's Fortress.
Monster 088: Ancient Beetle: Gul Highlands
Monster 089: Blood-Sucking Beetle: Ancient Ruins Forest
Monster 090: Ancient Scarab: Gul Highlands
Monster 091: Golden Scarab: Ancient Ruins Forest
Monster 092: Rolling Ripper: Destroyed Talta Village or fight a Squinting Cyborg (063) party in the Mecha Base Upper
Monster 093: Chief Rolling Ripper: Jibral Plains
Monster 094: Rolling Barb: Great Desert
Monster 095: Chief Rolling Barb: Great Desert
Monster 096: Gnashing Imp Trap: Ancient Factory
Monster 097: Glowering Imp Trap: This creature ONLY appears in Nene's Fortress.
Monster 098: Robber Clam: Sea Cube
Monster 099: Thief Clam: These are difficult to find. On the Western Island, fight a few Sea-Temple Turtles (148) and this creature should appear after a while.
Monster 100: Souleater: Jibral Highlands
Monster 101: Braineater: Ancient Ruins Forest
Monster 102: Bloodsucker: Northern Lal Mountains
Monster 103: Skillsucker: Great Desert
Monster 104: Acornivore: Forest of the Dead
Monster 105: Ravenous Acornivore: Devour Forest
Monster 106: Poison Helmet: Coastal Road
Monster 107: Shocking Acornivore: Southern Giant Ice Fields
Monster 108: Fanged Skimmer: Jibral Plains
Monster 109: Razor-Wing Skimmer: Devour Forest
Monster 110: Delirious Skimmer: Near the Exile Forest
Monster 111: Masked Skimmer: Ancient Ruins Forest
Monster 112: Coquettish: Fight a Crested Cockatrice (121) party Near Alumaru Village
Monster 113: Piper: Lal Highlands
Monster 114: Balloon Bomber: Found ONLY in Nene's Fortress
Monster 115: Clawed Bomber: Mecha Base Upper
Monster 116: Parvenu Pelican: Treasure Storehouse
Monster 117: Pelicon: Northern Giant Ice Fields
Monster 118: Phantom Pelican: Near Kelaso Village
Monster 119: Haunting Pelican: Giant Snow Fields
Monster 120: Shrike Cockatrice: Mural Valley West
Monster 121: Crested Cockatrice: Near Alumaru Village
Monster 122: Cockatrice: Jibral Plains
Monster 123: Mega Beak: Lal Highlands
Monster 124: Flame Raptor: Mural Valley East (Boss)
Monster 125: Tornado Raptor: Primitive Cube Deep Area
Monster 126: Ice Raptor: Northern Giant Ice Fields
Monster 127: Boreal Raptor: Southern Lal Mountains
Monster 128: Gotsu-Gotsu: Eastern Lot Wilderness, Western Lot Wilderness
Monster 129: Kochi-Kochi: Northern Giant Ice Fields
Monster 130: Bowa-Bowa: Primitive Cube
Monster 131: Soyo-Soyo: Ancient Ruins Forest
Monster 132: Snakeface: Near Talta Village
Monster 133: Visage Viper: Underground River
Monster 134: Snakween: Near Talta Village
Monster 135: Immortal Wings: Primitive Cube
Monster 136: Green Grunt: Lot Wilderness West
Monster 137: Blue Grunt: Canyon
Monster 138: Blue Infantry: Northern Lal Mountains
Monster 139: Red Infantry: Primitive Cube Deep Area
Monster 140: Orange Grunt: Jibral Highlands
Monster 141: Pink Grunt: Near Alumaru Village
Monster 142: Green Soldier: Eastern Lot Wilderness, Western Lot Wilderness
Monster 143: Pink Soldier: Primitive Cube Deep Area
Monster 144: Orange Soldier: Jibral Highlands
Monster 145: Blue Soldier: Southern Lal Mountains
Monster 146: Armor-Shelled Turtle: Laser Field
Monster 147: Glacier Turtle: Giant Snow Fields
Monster 148: Sea-Temple Turtle: Western Island
Monster 149: Land-Temple Turtle: Primitive Cube
Monster 150: Kelolon: Underground River, Sea Cube
Monster 151: Hyper Kelolon: Underground River
Monster 152: Kelolon Defender: Near Devour Village, Sea Cube
Monster 153: Balloon Toad: Fight a Kelolon Defender (152) party in the Sea Cube and kill the only the Kelolons (150). After a minute, the Kelolon Defender will become a Balloon Toad (153). If you’ve already defeated all of the Kelolon Defender (152) parties in the upper levels of the Sea Cube, engage a the Jelly Jolt (021) party on the Deepest Level of the Sea Cube.
Monster 154: Mad Eye: Destroyed Talta Village, Road to Jibral (Must be on Disc 2 or 3)
Monster 155: Impostor Eye: This creature ONLY appears in Nene's Fortress.
Monster 156: Cardinal Eye: Canyon
Monster 157: Fanatic Eye: Primitive Cube
Monster 158: Flying Needle Mole: Laser Field
Monster 159: Armaneedle: Giant Snow Fields
Monster 160: Explod-A-Mole: Canyon
Monster 161: Missile Mole: Wire Highlands
Monster 162: Fat Rat: Lot Wilderness East
Monster 163: Fat Pack Rat: Road to Jibral, Ancient Factory, Forest of the Dead
Monster 164: Big House Rat: Ancient Prison - Moat
Monster 165: Fireworks Rat: Ancient Factory
Monster 166: Pyre-Rat: Laser Field
Monster 167: Zombie Monkey: Devour Forest
Monster 168: Steel Monkey: Laser Field
Monster 169: Skeleton Monkey: In Devour Forest, start a Monster Fight between a Scavenger Wolf Ghost (038) and a Zombie Monkey (167) and wait for the Scavenger Wolf Ghost (038) to attack a Zombie Monkey (167). A Skeleton Monkey is the result.
Monster 170: Security Mecha Robo: Flying Fotress, Ancient Prison - Moat
Monster 171: Grim Security Mecha Robo: Mecha Base
Monster 172: Pachwork Puppet: This creature ONLY appears in Nene's Fortress.
Monster 173: Riot Puppet: Primitive Cube Deep Area
Monster 174: Defense Mecha Robo: Ancient Factory but undefeatable until you have the Red Device.
Monster 175: White Gear Defender: Northern Giant Ice Fields
Monster 176: Red Defender: Mecha Base Upper
Monster 177: Red-Mask Robot: This mecha appears ONLY in Nene's Fortress.
Monster 178: Spin-Laser Defender: Primitive Cube
Monster 179: Midnight Ghost: Ancient Hospital Ruins
Monster 180: Emerald Ghost: Ancient Prison - Moat
Monster 181: Gaudy Ghost: Southern Giant Ice Fields, Eastern Island
Monster 182: Lazy Spine Ghost: Eastern Island
Monster 183: Jumbo Ghost:Ancient Factory
Monster 184: Stupefying Ghost: Devour Forest
Monster 185: Red Razor Ghost: In the Primitive Cube, you must fight Bowa-Bowa (130) parties until you get a battle with both Bowa-Bowas (130) and Lazy Spine Ghosts (182). At this point, defend until one of the Bowa-Bowas (130) and one of the Lazy Spine Ghosts (182) combine to form a Red Razor Ghost (185).
Monster 186: Cursed Spine Ghost: In the Primitive Cube, fight a Wandering Sage (202) party. Eventually, it will summon a Cursed Spine Ghost. If the Wandering Sage (202) summons a Sanguine Slasher (199) first then defeat them and wait for the Wandering Sage to summon once more. This creature will NEVER appear again if you defeat all of the Wandering Sage parties.
Monster 187: Thief Ghost: Forest of the Dead
Monster 188: Bandit Ghost: Gul Mountains
Monster 189: Ninja Ghost: This undead appears ONLY in Nene's Fortress.
Monster 190: Robber Ghost: Primitive Cube
Monster 191: Hawk Eye: Mural Valley West
Monster 192: Ruby Halbird: Mural Valley East
Monster 193: Yellow Chiroptrident: Great Desert
Monster 194: Hunter Ghost: Gul Highlands
Monster 195: Assassin Ghost: Canyon
Monster 196: Shooter Ghost: Forest of the Dead
Monster 197: Fire Archer: Ancient Ruins Forest
Monster 198: Wandering Wrath: Ancient Hospital Ruins
Monster 199: Sanguine Slasher: In the Primitive Cube, fight a Wandering Sage (202) party. Eventually, it will summon a Sanguine Slasher. If the Wandering Sage (202) summons a Cursed Spine Ghost (186) first then defeat them and wait for the Wandering Sage to summon once more. This creature will NEVER appear again if you defeat all of the Wandering Sage parties.
Monster 200: Horned-Viper Trident: This mecha appears ONLY in Nene's Fortress.
Monster 201: Wandering Knowledge: Fight a White Gear Defender (175) party in the Northern Giant Ice Fields
Monster 202: Wandering Sage: In the Primitive Cube, this monster will NEVER appear again once it has been defeated. Allow it to summon a Cursed Spine Ghost (186) and a Sanguine Slasher (199) first.
Monster 203: Wandering Prophet: This creature appears ONLY in Nene's Fortress.
Monster 204: Wandering Reflection: In the Sea Cube, fight a Robber Clam (098) party
Monster 205: Lazy Bear: Gul Highlands
Monster 206: Polar Lazy Bear: Giant Snow Fields
Monster 207: Horned Lazy Bear: Laser Field
Monster 208: Thunder Bear: Southern Giant Ice Fields
Monster 209: Sentinel Mecha Robo Head: In the Ancient Prison – Moat, this mecha combines with a Sentinel Mecha Robo Body (211) to form a Sentinel Mecha Robo (213).
Monster 210: Electrogue Part A: In the Mecha Base Upper, fight a Security Electrogue (214). Either bring down its hit points, or, more easily, hit it with a fully charged physical attack to split it into an Electrogue Part A (210) and an Electrogue Part B (212).
Monster 211: Sentinel Mecha Robo Body: In the Ancient Prison – Moat, this mecha combines with a Sentinel Mecha Robo Head (209) to form a Sentinel Mecha Robo (213).
Monster 212: Electrogue Part B: In the Mecha Base Upper, fight a Security Electrogue (214). Either bring down its hit points, or, more easily, hit it with a fully charged physical attack to split it into an Electrogue Part A (210) and an Electrogue Part B (212).
Monster 213: Sentinel Mecha Robo: In the Ancient Prison – Moat, a Sentinel Mecha Robo Head (209) and a Sentinel Mecha Robo Body (211) will combine to make a Sentinel Mecha Robo.
Monster 214: Security Electrogue: In the Mecha Base Upper, a fully charged physical attack will cause this mecha to split into Electrogue Part A (210) and Electrogue Part B (212).
Monster 215: Spike-Arm Sentry: Primitive Cube Deep Area (Boss)
Monster 216: Scowling Dynamo: Primitive Cube Deep Area (Boss)
Monster 217: Double Axe: This creature appears ONLY in the Flying Fortress.
Monster 218: Black Double Axe: Mecha Base, Mecha Base Upper
Monster 219: Double Lance: Ancient Factory
Monster 220: Mad Scarlet Spear: Primitive Cube Deep Area
Monster 221: Sneezing Cyclops: Primitive Cube Deep Area (Boss)
Monster 222: Mechataclysm: Primitive Cube Deep Area (Boss)
Monster 223: Spellcaster: Mecha Base (Boss)
Monster 224: Soaring Globe: Mecha Base Upper (Boss)
Monster 225: Steel-Eating Tiger: Road to Jibral
Monster 226: Gold-Eating Tiger: Treasure Storehouse
Monster 227: Steel-Crusher Leopard: This creature appears ONLY in Nene's Fortress.
Monster 228: Howling Leopard: Ancient Ruins Forest
Monster 229: Ice Giant: Southern Giant Ice Fields
Monster 230: Crystal Giant: Sea Cube
Monster 231: Stone Giant: This creature appears ONLY in Nene's Fortress.
Monster 232: Gold Giant: Treasure Storehouse
Monster 233: Grinning Ghost: Forest of the Dead
Monster 234: Melancholy Ghost: Ancient Prison – Moat, Eastern Island
Monster 235: Chain-Gang Ghost: Gul Mountains, Eastern Island
Monster 236: Poleaxe Ghost: You must fight a certain type of ghost party on the Eastern Island to find this ghost. It is hard to find, so be patient.
Monster 237: Mad Fang Mammoth: Canyon
Monster 238: Albino Mammoth: Near Kelaso Village
Monster 239: Machine Gunner: Northern Giant Ice Fields
Monster 240: Flame Gunner: Primitive Cube Deep Area
Monster 241: Misfortune Mural: Mural Valley West
Monster 242: Evil Mural: Mural Valley West
Monster 243: Poison Mural: Mural Valley East
Monster 244: Chaos Mural: Mural Valley East
Monster 245: Hydrattler: Undersea Caverns (Boss)
Monster 246: Hot Hot Hydra: Primitive Cube Inside (Boss)
Monster 247: Poison Hydrattler: Exile Forest Caverns
Monster 248: Gorgon Hydrattler: Ancient Ruins Forest
Monster 249: Sandworm: Great Desert
Monster 250: Azure Scorpion: Giant Snow Fields
Monster 251: Centipede: Laser Field
Monster 252: Moody Dragon: In the Underground River, this dragon first appears only after all of the Kelolon (150) and Hyper Kelolon (151) parties are defeated behind the blue barrier near the Ancient Factory. This is the only dragon that will appear before you visit Kelaso Village.
Monster 253: Spark Dragon: Only appears in the Gul Mountains after speaking with Bauhm in Kelaso Village - Underground.
Monster 254: Pyro Dragon: Primitive Cube Deep Area (Boss)
Monster 255: Phantom Dragon: Only appears in the Great Desert on the world map after speaking with Bauhm in Kelaso Village - Underground.
Monster 256: Blizzard Dragon: Only appears Near Kelaso Village after speaking with Bauhm in Kelaso Village - Underground.
Monster 257: Amethyst Dragon: Only appears on the Coastal Road after speaking with Bauhm in Kelaso Village - Underground.
Monster 258: Jeelala: Treasure Storehouse (Boss)
Monster 259: Gorgo Beastfolk Warrior: Treasure Storehouse (Boss)
Monster 260: Winking Patroller: Drill Machine (Boss)
Monster 261: Flamboyant Dinoram: Lot Wilderness West (Boss)
Monster 262: Stonesaurus: Aurora Ruins (Boss)
Monster 263: Icefire Wolf Ghost: Ancient Hospital Ruins (Boss)
Monster 264: Rockwind Wolf Ghost: Southern Lal Mountains (Boss). Let this creature split into the Gale Wolf Ghost (041) and the Stone Wolf Ghost (042) BEFORE you kill it.
Monster 265: King Ghost: Forest of the Dead (Boss)
Monster 266: Dullahan: Road to Jibral (Boss)
Monster 267: Blazing Kirin: Baroy Town - Temple Basement (Boss)
Monster 268: Azure Abyssal Dragon: Sea Cube (Boss)
Monster 269: Azure Sentinel: Noluta Village (Boss)
Monster 270: Steel Giant: Mecha Base Upper (Boss)
Monster 271: Eat-Yeet: Devour Village (Boss)
Monster 272: Ghost Yeet: Eastern Island (Boss)
Monster 273: Scything Skull-Spider: In Pachess Town – Underground, allow this boss to summon the Skeleton General (082) BEFORE you defeat it, or you will never see the Skeleton General again.
Monster 274: Gold Scything Skull-Spider: Mecha Base (Boss)
Monster 275: Jumbo Mecha Robo: Nene's Fortress (Boss)
Monster 276: Land Shark A: Nene's Fortress (Boss)
Monster 277: Land Shark B: Nene's Fortress (Boss). Land Shark A becomes this creature as you are fighting it.
Monster 278: Land Shark C: Ancient Ruins Forest (Boss)
Monster 279: Mechosaur: Primitive Cube (Boss)
Monster 280: Szabo: Flying Fortress (Boss)
Monster 281: Grand Szabo: Nene's Fortress (Boss)
Monster 282: Ultimate Szabo: Chamber of the Cauldron (Boss)
Monster 283: Silent Ku: Flying Fortress (Boss)
Monster 284: Grand Silent Ku: Nene's Fortress (Boss)
Monster 285: Heat-Wave Sai: Flying Fortress (Boss)
Monster 286: Grand Heat-Wave Sai: Nene's Fortress (Boss)
Monster 287: Raging Kesu: Flying Fortress (Boss)
Monster 288: Grand Raging Kesu: Nene's Fortress (Boss)
Monster 289: Turbulent Mai: Flying Fortress (Boss)
Monster 290: Grand Turbulent Mai: Nene's Fortress (Boss)

Just a little addendum from gamer JotaroRaido: Here is a list of which monsters can be missed and what areas they are found in, so if you're past the mentioned spot and don't have them in your record...See the addendum below, courtesy of gamer Ellyone.

Flying Fortress: 036, 056, 061, 066, 217
Pachess Town (monster summoned by Scything Skull-Spider): 082
Nene's Fortress: 059, 073, 083, 084, 085, 086, 087, 097, 114, 155, 172, 177, 189, 200, 203, 227, 231
Southern Lal Mountains (Rockwind Wolf Ghost splits into these two monsters after a short time in battle): 041, 042
Primitive Cube (monsters summoned by Wandering Sage): 186, 199

And a helpful addition from Ellyone:
If you do unfortunately miss a monster, you can download the Ultra Hard Mod DLC, start a New Game+ and play through the game skipping cutscenes and with your power intact. This will allow you to get to missed monsters quickly for another shot.

The guides above give you a very good indication of what needs to be done to get the achievement, this isn't a guide but a tip that saved me a lot of time because I missed killing Servant Mecha Robo A & B during the fight with Yasato.

I only missed 2 monsters in my first playthrough and didn't really want to have to play the entire thing again because of 2 monsters!

With the "Ultra Hard Mod" DLC for the game, it gives you the option to start a "new game +" and you can select to use an existing save profile and keep all of your ranks, accessories and most importantly Item & Monster record stats for a new game.

I was able to skip all the cut scenes, not chat to anyone, and just run through the story and get to the enemies I needed at the end of disc 2 in 3-4 hours, rather than having to play the entire game again and as soon as I killed them the achievement unlocked.

I created a checklist for this to keep track of my progress. As usual I shared it on Google Docs: Google Docs - Blue Dragon

See the 7th page of the spreadsheet (titled "Enemies"). Simply download your own copy of the document and enter a "1" in the red box on each row as you defeat the monster. Missable monsters are highlighted.

For this achievement you must fight AND defeat every monster in the monster log book. There are 290 in all (these include all regular enemies plus bosses and secret enemies).

Most can't be missed, but a few are missable, mainly in the Primitive Cube and a few elsewhere.

I recommend going through this guide:

http://www.gamefaqs.com/console/xbox360/file/927950/47047

and marking/ make a note of missable enemies (I did this and it worked like a charm).

This will more than likely be one of your last achievements, fill in the whole log and the achievement is yours.