SRW 30: L-Gaim Buster Launcher Event (The Dictator)[Posaydal Giwaza Final Fight エルガイム Mk-II スパロボ30) 

Using the buster launcher leaves the L-Gaim completely drained because it wasn't build to use that kind of weapon. It didn't matter in the anime since Giwaza's death ended the battle, and even in the context of the game, they can just fix the L-Gaim after the battle is over.