[Nyara]

I don't like Duosion, he's just too weak to handle special attacks, even with Eviolite. And even if he set ups, he's still OHKO by any strong physical attacker. Also, the Psyshock variant is heavy checked by any thing with double or quad resistance to Signal Beam and with good defenses (sadly for him, that combo is really usual). Even with 1+ Calm Mind, he's still unnable to handle strong special attacks at all because it's horrible HP base and uninvestment special defense. Sadly for him, Psyshock and in some degree Psychic are not really strong attacks, and Hidden Power/Signal Beam are just too weak to deal the correct damage at all. Taking in account Duosion will be outspeed always if he's not on Trick Room, and he's adove avarage at best with Eviolite, it's quite easy to deal him more than 50% of damage and render him's recover useless, the same goes with him's special defense at even 1+ Calm Mind. Recover just works on Calm Mind wars or stuff like that, but those things are actually pretty rare on the tier, maybe to combat back a Quiver Dancer?

Duosion is just a high-risk, somewhat decent reward Pokémon. It can be high-risk/high-reward if your opponent is stupid and lose valuable turns doing stuff like Toxic him while he have Magic Guard, or if you make the combo of Duosion + Trick Room, but because he needs to set up, the amount of turns under Trick Room will be really low, and he'll sweep at most 2 Pokémon. I give him a point for being able to handle Toxic Spikes and random Switch-In with Will-O-Wisp without trouble, but Kadabra does the same better. Also, Kadabra have more offensive power and movepool than Duosion, even if Duosion is already on 1+ Calm Mind.

Other bad point is the fact that Duosion is just unnable to handle Ghost/Dark/Bug types attacks (being 2HKO by almost anything with those, and even OHKO), any Pokémon with those attacks will end any try to sweep or do anything at all.