Assault Suit Leynos

To get this trophy you must complete the game while unlocking all of the different weapons along the way. New weapons are awarded based on how well you do on the different stages.

You will unlock this trophy alongside "Classic Hero" if you finish your Classic Mode playthrough after earning "Old Tricks". If you can shoot down just the boss ship in stage 1 without killing any other enemies, you will unlock all of the weapons at once. Then just play through the rest of the game as you normally would.

You can also get this trophy alongside "Arcade Hero". I got it after finishing Arcade Mode while earning an "A" rank on one stage, "B" on another, and "S" (the highest rank) on the rest. The trophy can still be earned if you continue mid-stage, but you will miss out on the stage-related trophies and will not get "S" rank on the stage where you continued, so avoid doing that if at all possible.