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.

The classic Pokémon games must make the jump to Switch

Pokémon Home transferring guide, how to transfer from Pokémon Go, Legends Arceus, Brilliant Diamond and Shining Pearl explained

Switch, SUBS] Game Boy Games Added to Nintendo Switch Online, Game Boy Advance Games Added to Expansion Pack @ Nintendo eShop - OzBargain

Successful link cable Pokémon trade from openFPGA Game Boy Core (using Memories) to Game Boy Color (using Everdrive X7) : r/AnaloguePocket

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

Spoofing Pokemon Trades

Nintendo is adding Game Boy and Game Boy Advance games to Switch Online today

LuigiBlood's Blog — What's the deal with the GB/GBA Emulator Leak?

Pokémon Trading Card Game (video game) - Bulbapedia, the community-driven Pokémon encyclopedia