Pokémon Go trade back evolution

I tried google searching and I couldnt find any definitive answer so Ill try asking here. I have a Kadabra and a Machoke that I want to evolve and as far as I understand, trade evolutions is a new feature. Now, when Pokémon Go first introduced trades a couple years ago I know that trade backs were not allowed but Im wondering if thats different now. If not its fine since Ill just continue the monotonous grind for candies but these could really help me