Pokemon Trading Has Been Tested On Nintendo Switch Online's Game Boy Emulator

Pokemon Gen 1 to 3 games haven
Pokemon Gen 1 to 3 games haven't officially made it onto NSO yet, but a programmer demonstrated that trading should work flawlessly.

Is the Game Boy & Game Boy Color title added to 'Nintendo Switch Online'? - GIGAZINE

Game Boy And GBA Coming To Switch Online Today

We're Getting a New (Unofficial) Game Boy

Alleged Leaks Reveal Game Boy And Game Boy Advance Games Coming To Nintendo Switch Online - Bounding Into Comics

22 Game Boy Advance Games We'd Love To See Added To Nintendo Switch Online

Nintendo Switch Online Game Boy and Game Boy Advance games

The best fan-made Pokémon games

Official Nintendo GBA emulator for Switch Online leaks

Game Boy and Game Boy Advance games are coming to Nintendo Switch Online today - The Verge