I want one in Pokemon Go but even if I have 50 candy I can't evolve.
To evolve a Galarian Farfetch'd into Sirfetch'd in Pokémon Go, you first need to have the Galarian Farfetch'd as your Buddy Pokémon. Once you've done this, you'll need to collect 50 Farfetch'd Candy and make 10 Excellent throws while Galarian Farfetch'd is your Buddy Pokémon
So you probably haven't done the 10 Excellent throws yet.
Source
Hope this helps!
To evolve a Galarian Farfetch'd into Sirfetch'd in Pokémon Go, you first need to have the Galarian Farfetch'd as your Buddy Pokémon. Once you've done this, you'll need to collect 50 Farfetch'd Candy and make 10 Excellent throws while Galarian Farfetch'd is your Buddy Pokémon. This may sound difficult, but, thankfully, you don't need to perform these Excellent throws in a row nor will the counter reset if you decide you don't want the Galarian Farfetch'd to be your Buddy for a while.
To evolve a Galarian Farfetch'd into Sirfetch'd in Pokémon Go, you first need to have the Galarian Farfetch'd as your Buddy Pokémon.
Once you've done this, you'll need to collect 50 Farfetch'd Candy and make 10 Excellent throws while Galarian Farfetch'd is your Buddy Pokémon.
This may sound difficult, but, thankfully, you don't need to perform these Excellent throws in a row nor will the counter reset if you decide you don't want the Galarian Farfetch'd to be your Buddy for a while.
Hope I helped!