>>18377483252 SpA Mega Charizard Y Focus Blast vs. 252 HP / 252+ SpD Assault Vest Tyranitar: 292-348 (72.2 - 86.1%) -- guaranteed 2HKO
>implying anyone actually runs a special defense T-tar anymore252 SpA Mega Charizard Y Focus Blast vs. 252 HP / 4 SpD Assault Vest Tyranitar: 408-480 (100.9 - 118.8%) -- guaranteed OHKO
>>18377486252 SpA Mega Charizard Y Focus Blast vs. 252 HP / 252+ SpD Heatran: 210-248 (54.4 - 64.2%) -- guaranteed 2HKO after Leftovers recovery
0- Atk Heatran Stone Edge vs. 4 HP / 0 Def Mega Charizard Y: 292-344 (97.9 - 115.4%) -- 81.3% chance to OHKO
4 SpA Heatran Ancient Power vs. 4 HP / 0 SpD Mega Charizard Y: 196-232 (65.7 - 77.8%) -- guaranteed 2HKO
Focus Miss shits on both mons.
T-tar will hardly be fucked, regardless of weather change.
Heatran gets fucked if it misses that stone edge, or wastes a turn trying to set up.
And that's if they're not switching into a focus miss. If they do, and focus miss hits, then they're dead.
Unless of course Focus Miss misses, then in that case yeah, they're viable counters.