If you just picked up Rockman ZX place Rockman Zero 3 or Rockman Zero 4 in the GBA slot. When you do this you will get a chance to face off against Chilldre Inarabitta Hellbat Silk and Fenri Lunaedge. Each “Zero” Game Boy Advance game adds in four bonus bosses. If you manage to complete all eight by using both games, Zero will be able to pick up a powerup with a mysterious function. Rockman ZX is one of the few games to take advantage of the GBA slot for something other than rumbling. Feel the Magic XX/XY is another game that paid attention to what was in the cartridge slot, but it was only for a few extra Sega related costumes.