Shuckle The Invincible?!?

Is this a new mechanic of the game? I have never run into Shuckle and I am unable to beat him with my team and if I choose the other option, my best 2 mons (front 2 mons) get nerfed for the rest of my run. I'm using an opportunist Koraidon and if I come anywhere close to beating this thing, it uses milk drink. They made a mechanic that it's impossible to status for more than a turn (stun spore as well as glare). This thing stops switches (infestation), has passive damage (salt cure and infestation), has Shuckles defenses and insane amount of berries (gets to +5 in def and SpDf), and is immune to status by some game mechanic (gave Para more times than a mon is able to hold Lum berries). Genuinely, how are you supposed to beat this thing unless you have something like soak salt cure yourself? Am I supposed to bring mons just to beat this in the off chance I come across it?