Try Politoed, as it counters Charizards weather (turning it to rain, destroying Solar Beam) and is resistant to Fire STABs.
Trollitoad (politoed)@ Life Orb
EVs:252 HP, 252 Atk, 4 Sp.D
Waterfall is for OHKOing Charizard Y, the others are filler. Body Slam can Paralyze, making you faster, and Hypnosis puts him to sleep.
252+ Atk Life Orb Politoed Waterfall vs. 0 HP / 4 Def Mega Charizard Y in Rain: 478-564 (160.9 - 189.8%) -- guaranteed OHKO
And this is all Charizard can achieve
252 SpA Mega Charizard Y Fire Blast vs. 252 HP / 4 SpD Politoed in Rain: 51-61 (13.2 - 15.8%) -- possible 7HKO
252 SpA Mega Charizard Y Solar Beam (60 BP) vs. 252 HP / 4 SpD Politoed in Rain: 152-180 (39.5 - 46.8%) -- guaranteed 3HKO
252 SpA Mega Charizard Y Focus Blast vs. 252 HP / 4 SpD Politoed: 152-179 (39.5 - 46.6%) -- guaranteed 3HKO
As you can see, Drizzle makes Charizard useless, and Politoed can easily OHKO it, making Politoed a reliable counter.