Gravity Rush [VITA]: [NOTE: The extra content is only on the game card for the US release.]

Pokemon Red/Blue/Yellow [GB/GBC]: Certain Pokemon can only be obtained through trading across other versions of the game. [NOTE: This content can be hacked to be made accessible through glitches and cheat devices.]

Sonic & Knuckles [GEN]: Additional games can be unlocked if a Sonic 2 or Sonic 3 cartridge is attached.

Zelda: Oracle of Ages / Seasons [GBC]: Some characters and item upgrades are only available after obtaining passwords from the other game.