Verified answer

yes the chip in the corner of the games means they will work on the old fat game boy when it's slid on

All 1st Generation (RBY) & the majority of 2nd Generation Pokémon (GS) titles will work the with the original GBY. The first generation (which includes Pokémon Yellow) was release prior to the GBC being released, so they'll work just fine. They did, however, include enhancements for the Super Gameboy (SNES) to make them a bit more enjoyable (with some color & a custom background).

The 2nd Generation Pokémon titles were designed to be dual-bootable, so they were compatible with the GBY & were enhanced with the GBC. Pokémon Crystal was NOT designed to be dual-bootable, so you can't play that version on the GBY.

Hope this helps!

pokemon Blue, Red, Yellow, Gold and Silver, (NOT crystal) are actually all original gameboy games even though the gameboy color was out when Gold and Silver came out. The box for G/S advertises them as gameboy color but they are actually original.

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