I understand what you are trying to say, but I don't think the way of evolving galarian Farfetch'd has to change.
In Pokemon sword a wild Farfeth'd has 50% chance of be holding a leek. This item rises Farfetch'd crit by 2 stages so if you have it holding one he has 50% chance of landing a critical hit with a regular move. Also, if your farfetch'd knows either leaf blade or night slash it will always land a critical hit, so you just need to find a trainer that can handle 3 crits.
Note: I used a spoiler bar because I didn't want to cover a lot of space.