What is a good counter to mega charizard y's and common switches?

i know “How would I counter Charizard Y?” is already there, but I am asking for a counter for his common switches, like Rotom-Wash. it is so annoying when you could kill a really strong Pokemon, and then they switch out for a counter which takes little to no damage from your move. so I want a Pokemon that forces Charizard to switch, only to land a super-effective hit on his switch choice. It can be banded, choiced, I don’t care, as long as it works. I will even use a set-up if I have to, just help me please.

i forgot to add, please can it kill of charizard as well.

Pleaselog inorregisterto add a comment.

Gastrodon is quite a force to be reckoned with. Especially if it has Stone-Edge. I haven’t seen many Gastrodons with SE so I’mguessingits not a common move to have on a Gastrodon. Which is all the better as SE has a 50% Chance to OHKO Zard Y

0- Atk Gastrodon Stone Edge vs. 0 HP / 0 Def Mega Charizard Y: 272-324 (91.5 - 109%) – 50% chance to OHKO

When your opponent switches to Rotom Wash Gastrdon will have no problem stomaching its hits as Gastrodon easily resists Rotom-W’s 2 main STAB moves. Gastrodon doesn’t have the power to OHKO Rotom-W but it can slowly chip away with Toxic.