How can I trade specific Pokémon?
Solution 1:
On January 28th 2020, it has been officially confirmed that Pokémon Home will feature the Global Trade System.
Pokémon Home will feature a free version and premium version. Through the GTS, the free version will allow you trade up to 1 Pokémon at once time while the premium version will allow you to trade up 3 Pokémon at once.
The Global Trading System (GTS) did not make its return in Sword and Shield, so trading in this manner is not a native feature in these games.
As an alternative, you could always join a Reddit or Discord group that could be used as a mock-GTS. A friend of mine is apart of a Discord group where he can request specific Pokémon with IV spread, moves, etc... and somebody will hook him up with one using the link trade feature.