Short answer: Sometimes, but inventory is wildly inconsistent. GameStop's retro stock varies dramatically from store to store, making it a gamble for Game Boy hunters.
The website lists Game Boy, Game Boy Color, and Game Boy Advance cartridges, but availability is a mirage. Most listings show "Unavailable" or "Store Pickup Only" with zero local quantity. Don't rely on the website for accurate stock.
Only about 30% of locations even have a dedicated "Retro" section. When they do, selection skews heavily toward common loose cartridges—think Pokémon, Mario, Kirby, and annual sports titles. Prices range from $5 to $40. Complete-in-box (CIB) or boxed games are virtually nonexistent.
GameStop accepts loose GB/GBC/GBA cartridges for trade credit, typically offering $0.50 to $5 per game. They do not purchase boxes or manuals separately.
Pro Tip: Call ahead. Ask specifically: "Do you have Game Boy games in the retro case?" It saves a wasted trip.