>>16727978I would suggest
-Fire Blast
-Solar Beam
-Focus Blast
-Dragon Pulse/HP Ice/Roost/Flare Blitz/Flame Charge
Air slash isn't that useful since Drought Blast hits harder for most things you want to attack with Air Slash or you have a coverage move for them. Not counting the type combinations that don't have pokemon yet (Dragon/Fighting and Fire/Water), the ones that Air Slash would hit harder than Drought Blast are:
Fire/Fighting - Infernape, Emboar and Blaziken (which is ubers if you're playing with smogon rules)
Water/Fighting - Solar Beam
Dragon/Water - Dragon Pulse
Dragon/Fire - Dragon Pulse
So basically, Emboar and Infernape. Out of curiosity, Thick Fat Mega Venusaur takes more damage from Fire Blast than Air Slash.
252 SpA Mega Charizard Y Fire Blast vs. 252 HP / 252+ SpD Thick Fat Mega Venusaur in Sun: 200-236 (54.9 - 64.8%) -- guaranteed 2HKO
252 SpA Mega Charizard Y Air Slash vs. 252 HP / 252+ SpD Mega Venusaur: 182-216 (50 - 59.3%) -- guaranteed 2HKO
Same for Fire/Bug Volcarona
252 SpA Mega Charizard Y Fire Blast vs. 4 HP / 0 SpD Volcarona in Sun: 301-355 (96.4 - 113.7%) -- 81.3% chance to OHKO
252 SpA Mega Charizard Y Air Slash vs. 4 HP / 0 SpD Volcarona: 272-324 (87.1 - 103.8%) -- 25% chance to OHKO
Please correct me if I'm wrong or forgotten something.