Connection bonuses:
Have the Game Boy Advance game Super Robot Taisen: Original Generation in the cartridge slot. Start a new game or load a saved game file to get the OG1 Choker that increases your SP by 100.
Have the Game Boy Advance game Super Robot Taisen: Original Generation 2 in the cartridge slot. Start a new game or load a saved game file to get the OG2 Pendant that increases your HP by 250.
Completion bonus:
Beat the game and load your cleared saved game file to start a new game with all previously earned money and items.