Tapu Lele- Win Needs Flash Cannon
Gardevoir-Mega - Win if no focus blast Needs Flash Cannon
Magnezone - Mostly Win Needs to have Rock Tomb + Dodge Zap Cannon
Jumpluff - Win if taunt (and don't get totally wrecked by sleep turns) Grassium bypasses Taunt
252 Atk Choice Band Kartana Sacred Sword vs. 0 HP / 80 Def Heatran: 332-392 (102.7 - 121.3%) -- guaranteed OHKO
Pinsir-Mega - Win
Porygon2 - Win if taunt You can actually still get KO'd before you KO them
Volcarona - Win With Rock Tomb
Deoxys-S - Win if taunt With Rock Tomb (loses to Specs)
Vivillon - Win if you don't get bodied by sleep turns Requires Taunt
Zapdos - Never faced this on ladder I have no idea lmfao Lose
Gigalith- Win With Flash Cannon
Heracross-Mega - Win Depends on who's faster
Latios -Win Depends on moveset
Regice - Mostly win Requires Taunt
Salamence - Beats Outrage, DDance, IDefense, Roost and scarf variants Requires Taunt + Flash Cannon
Aerodactyl-Mega - Win Flash Cannon
Buzzwole - Lose Depends on Speed
Darmanitan - Win if no Superpower (or if it's endure custap Zen Mode rofl) You eat a Superpower
Marowak-Alola - mostly win Low Kick is death
Rhyperior - Win Assault Vest eats multiple Flash Cannon and Banded/Z move Wreck you
Alakazam-Mega - Lose if focus blast Encore Disable also beat you, for the most part
Hydreigon - mostly Win With Flash Cannon vs Scarf and assuming you don't get flinched or crit at all-
Muk-Alola - Win if EP Taunt
Breloom - Win only if you're Timid
Lilligant - Win Taunt
Riolu - Win Taunt
Roserade - Win Taunt
Did some fixes.
Personally, I find Heatran to be way too stretched between its 4 moveslots to be worthy of A-
The fact that you need Taunt and Flash Cannon for so many matchups mean you inevitably have to sacrifice something between Rock Tomb, Earth Power, and Overheat.
This is moreso just speculation, but an optimal set could perhaps be Ancient Power, Overheat, Flash Cannon, and Taunt?
Ancient Power typically covers the Charizard combo you previously needed Rock Tomb + Earth Power for, so long as you have sufficient bulk and special attack, thus freeing a moveslot so you can get all your essentials packed in. You do sacrifice a couple of Rock Tomb matchups, sadly.