How do you counter Mega Charizard Y?

Question

currently its one of if not the most used mons and can chunk well, anything really. if more mons were added well you have more counters like walking wake, thermal exchange baxcalibur or ogerpon wellspring but currently the only mon that really counters it I know of is aerodactyl. some other mons you could maybe use would be flash fire ceruledge, kommo-o, mega dragalge and hisuian typhlosion but all those just do neutral damage and dont outspeed mega charizard. maybe you could use milotic, toxapex or mega floette but idk.

tldr how to counter mega charizard y other than aerodactyl

edit: just as a fyi the currently most used moveset is protect, heat wave, solar beam and weather ball all at above 90% use, the next most used are air slash, overheat and helping hand at around 2.5% use, so mainly looking for something that lives a weather ball/solar beam and can revenge ko it or something that outspeeds and can ko it but anything that counters it can be included in the answer.

Comments

Assuming you mean Champions Reg M-A or B VGC; these are both viable options to beat Charizard Y, speaking as someone who used it for the entirety of Season M-1 and 2.
Mega Tyranitar Sandstorm teams set up Sandstorm both when Ttar switches in and again when it Mega Evolves, making it almost impossible to gain weather control from them, and then Sand Rush Excadrill or +50% SpD Ttar OHKO with Rock Slide.
Choice Scarf Kleavor can unexpectedly outspeed and either OHKO or set up Stealth Rocks which then take 50% of Charizard's health with Stone Axe.
Aerodactyl, Garchomp, and Sneasler all outspeed and OHKO with Rock Slide.
Rain teams including mons such as Pelliper, Archaludon, Basculeigon, Mega Dragonite (and Mega Swampert in M-B) turn off Charizard's sun, wall Heat Wave with Wide Guard, and can 1/2-shot with any combination of Electro Shot, Weather Ball, Wave Crash, 2 stacks of Last Respects or Thunder.
Not a complete list, just wanted to mention a few things

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After fiddling with a damage calculator here are some mons I found to be able to 2hko mega charizard y and wall it pretty well:
Mega dragalge can sludge bomb turn 1 and Draco meteor second turn
Hisuean arcanine can ohko with head smash/rock slide and also outspeeds modest charizard with max speed if you invest in max speed with beneficial nature
You can charizard can ko itself if it runs ancient power
Like ax said garchomp ohko es with rock slide
Kommo-o with clangerous soul and clanging scales 2hko but their not going to let you set up

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Well rain teams are an option if, you can predict they mega evolve, you can use rain dance then use a fast water special attacker