FINAL FANTASY XIII-2

These are listed in order of the difficulty I found them to be. Your mileage may vary based on your play style and party setup.

Don't forget that for certain endings, you must actually visit a second area after beating a boss in the non-story-approved way. Usually these places will be listed by "Area Name ???AF" I can't remember which all of the places are for this, but if a new area appears after you've defeated a boss make sure to visit it, especially if you've gone back and closed the gate in order to rewind the story and refight bosses.

1) When you're first going through the story you can actually get a Paradox Ending when Lightning offers you to stick around in New Bohdum during your dream. Say yes, and boom. The ending will show, and you'll be kicked back with the option to return to New Bohdum and this time say no.

2) Close gate on Acadamia 4XX AF. With your Paradox Scope on, go talk to Alyssa and DO NOT skip the cutscene OR take the artifact.
**NOTE** Sensei zack h19 pointed out that you don't get the option to reject the artifacts until AFTER you've given Alyssa all of the pieces. So in other words, turn in all of the artifacts, make sure to actually sit through the cutscene that follows, and then reject the artifact when she tries to give it to you.

3) With the paradox scope on, close the gate for Augusta Tower 200 AF. Head up to fight Proto Fal'cie Adam. Don't forget that when you are on the elevator, at each floor you don't need to leave the elevator, just examine the switch and continue up to the top.

4) Close the Bresha Ruins 005 AF gate. Go fight Atlas without weakening him.
**NOTE** SamuraiPanda89 has warned not to skip the cutscene when you first approach Atlas, as this may result in missing the necessary dialogue options to fight him in his un-weakened state.

5) This time, close the gate on Sunleth Waterscape 300 AF. Fight His Royal Hugeness, then immediately after fight him again.
(Thanks to LazTurn for pointing out you don't need the Paradox Scope for these two.)

6) Close gate on Academia 4XX AF. Accept the artifacts, proceed with the story as usual until you reach the Dying World. Turn on your Paradox Scope, and fight Caius. I did this with Noel at 5 x 99 and 1 x 40 (It was Saboteur, I believe). I also forgot to equip his Ultimate Weapon, so it is possible to do it without, just a little harder. When the fight starts, attack him as a commando until the stagger bar is locked (it will change colors slightly, and drain slower). One full ATB gauge attack should be good. Now switch to Ravager until he's stunned, then switch back to Commando. This should be enough to finish him off the first time. He'll revive, and you will have the opportunity to heal up if you don't attack him right away. Repeat this process, and don't forget to use your Javalin attack if you need to.

Mise64 has provided an alternate method for fighting Caius if you are having trouble with mine. He says: Start the fight as a Sentinel and use Mediguard while Caius is attacking. Eventually he will step back, so when he does switch to Saboteur and use Wound. Keep doing this until he's down to one third of his life and then switch to Commando and take him out.

7) Close gate on Oerba 200 AF. Defeat Caius. If you're having trouble with him, make sure to get poison on him early, and a Med-Med-Med or Syn-Med-Med paradigm helps for quick recovery.

8) Close gate on Acadamia 4XX AF. Proceed with the story until you get to the Void Beyond, and then turn your Paradox Scope on. Defeat Caius as Serah. I suggest bringing along a strong Commando such as fully-leveled Odin and a strong Sentinel such as Bunker Beast or Silver Chocobo.

An alternate method (albeit quite a bit longer, but much easier) is to bring along Bunker Beast (or another strong sentinel) and have Med-Sen / Sab-Sen / Rav-Sen - For the duration of the fight, you will be using Sab-Sen and (if necessary) switching to Med to heal when you or Bunker goes red. Continue to use Deshell until it sticks, then hit him with Wound over and over. When he casts Absolution or Body & Soul, dispell until all the buffs are gone (except the heart icon and the wings icon, you can't dispel those.) and then repeat with Deshell & Wound. Once he reaches 25% max health, he will no longer buff himself and you can switch to Rav-Sen or Com-Sen and finish him off....finally. Expect a long fight.

9) Not difficult as far as fighting, but it requires you to have every fragment - which basically means this will be the last achievement you get in the game. In order to get this, you have to return to Valhalla with the Paradox Scope on, AND all 160 fragments. You don't need to close the gate on 500 AF as you'll be right at the end again, just run down the final walkway. All the cutscenes can be skipped, right up to the end credits (twice). After that you should get a loading screen and then the secret ending.