As of now, there aren’t any specific details about how Farfetch’d evolves into Sirfetch’d; we only know that it happens after “experiencing many battles” — which sounds like the usual method of evolving after leveling up, but it’s still not confirmed.
It’s also not certain if Sirfetch’d will be one of the select Pokemon that can Gigantamax either.
Sirfetch’d also gets a brand-new move: Meteor Assault. It’s the one depicted in the trailer, and it seems similar to Hyper Beam in that it is a very powerful move that leaves the user unable to act on their next turn.
The mention of leaving battle if the leek should wither doesn’t sound like it indicates a new ability, either. The official description says Sirfetch’d retires from battling entirely if the leek wilts, and its sole ability appears to remain Steadfast.
We’re getting ever closer to Pokemon Sword and Pokemon Shield’s release date of November 15, and we’ll likely be seeing at least one more reveal in this style. Sirfetch’d’s reveal is the first new Pokemon announced as a version exclusive, so a Shield exclusive announcement is likely coming soon.
