Mr. Mime is weak to Ghost, Poison and Steel. In addition to STAB Psychic, it can use Light Screen and Reflect to reduce special and physical damage respectively. Steel-types are probably the best choice here. Dark-types aren’t super-effective, but still useful here to negate Psychic.
If you followed our advice, Alolan Muk can punish Mr. Mime with super-effective Poison Jab. Meanwhile, Alolan Persian can spam Nasty Plot until Light Screen wears off, then blast it with a neutral Dark Pulse. The worst Mr. Mime can do is Double Slap, which isn’t all that much.
Slowbro is weak to Grass, Electric, Bug, Ghost and Dark. This one can use STAB Psychic and Surf, Yawn to cause Sleep on the next turn, and Calm Mind to raise Special Attack and Special Defense. Especially if Reflect or Light Screen is still up, you really want to bash it with super-effective hits.
Jynx is weak to Fire, Rock, Bug, Ghost, Dark and Steel. You’re spoilt for choice. Like the one you may have fought, it uses STAB Psychic and Ice Punch, plus Lovely Kiss to cause Sleep. Compared to Slowbro, it’s less of a threat, but don’t underestimate it still.
Finally, Sabrina’s Alakazam can use STAB Psychic, plus Night Shade to deal 44 fixed damage. This fully evolved Abra has high Special Attack and Speed, making it a potent attacker, but it has terrible Defense. Alolan Muk or Persian will completely laugh at its face.
Survive Sabrina’s mind-bending assault and she’ll give you her Marsh Badge and TM33 Calm Mind. If you hadn’t seen it, Calm Mind raises the user’s Special Attack and Special Defense at the same time. It’s great when facing a special attacker that you can safely wall.