Heavy Weapon

Likely the hardest trophy in the game. Once you complete the main mission mode, this will unlock. It basically requires to you defeat every single boss in the game without dieing. If you die, you have to restart from the beginning. The Support Chopper will drop off upgrades during every transition to another boss.

General Tips: You're not trying for the quickest time so go for the safest route instead. Some bosses have extra guns that you can destroy so there is less chance of you being hit by something. Save your nukes for the last boss.

Go here Heavy Weapon Boss Videos to view the videos. Below I've written up a little text information regarding each boss.

Boss 1 - Twinblade: You can destroy the two missile launchers if you want to. Other than that just avoid the 4 missles and destroy the boss.

Boss 2 - Battleship: You can take out the 4 turrets if you want to. Once they are gone, destroy the center.

Boss 3 - War Blimp: Watch out for the roto mines and the raining fire. The boss will switch back and forth between the 2 attacks. Just keep attacking.

Boss 4 - War Wrecker: Just watch out for the wrecking ball. It is the only form of attack this boss has. Watch the video to learn the pattern.

Boss 5 - Gorillazilla: Try to destroy the missiles he throws out before they explode. If they explode, the release six energy balls you have to avoid. Once he's thrown the missles, he'll jump over to the other side of the screen. Just go underneath him and repeat.

Boss 6 - Eyebot: Destroy the six ends on his tentacles. If one of these lights up, do not stay beneath it. Once they are destroyed, continue to destroy the center while avoiding the standard attack.

Boss 7 - Head Zeppelin: Use your attack spread to eliminate the missiles he shoots out. When he does his bomb sweep, shoot at an angle up and then above you, while moving to the other side. Watch the video to see how.

Boss 8 - Mechworm: Wherever the sand gets disturbed is where this boss is coming up from. Get to the side and attack him while he leaps through the air.

Boss 9 - H-Bot: Destroy his two sides and then keep constant fire on him. He'll shoot some missiles you need to look out for but once he loses his sides, he'll shoot beams from his eyes. They aren't large, but avoid them nonetheless. You'll need to move side to side to avoid his jumps.

Boss 10 - Twinblade: Same as before but has more plasma guns on the side that shoot out.

Boss 11 - Battleship: The turrets will shoot at a quicker speed on this upgraded version. Same technique exists.

Boss 12 - War Blimp: More roto mines are released and the rain of fire is a little more difficult to avoid. Still not hard to get by.

Boss 13 - War Wrecker: When the wrecking ball hits the ground, it will throw up rocks that can damage you. Keep constant fire and stick to the same pattern as before.

Boss 14 - Gorillazilla: Same as before just a different jump pattern. Destroy those missiles to make it easier for you.

Boss 15 - Eyebot: Same as before but just a bit quicker. Same technique applies here.

Boss 16 - Head Zeppelin: Almost the exact same fight. Do what you did for the first one and you'll be perfect.

Boss 17 - Mechworm: Same attacks and technique here. He launches more rocks this time around though.

Boss 18 - H-Bot: Same attacks used here as well. Do what you did before and you're good to go.

Boss 19 - Secret Weapon: Three stage boss fight.
Stage 1: Avoid those lasers at all costs. Use a nuke if you have to and are about to get hit. The lasers can go straight down, cross each other, or cross each other while they wave back and forth.
Stage 2: Stay under him the whole time. Shoot straight up so that you destroy the atomic bombs he drops. If one of them is about to hit the ground, use a nuke. The only other attack he does here are pink plasma shots.
Stage 3: Easiest stage. Shoot him and the homing missiles that get close to you.