Didn't want to clutter the thread further, but I still disagree with including Thunder Punch and Fire Punch on Mega Lopunny:
As I already mentioned, Thunder Punch is only useful for Gyarados. That's it. Return still chunks it. Return still (slightly) outdamages Thunder Punch on Azumarill, while High Jump Kick hits Scizor harder:
252 Atk Lopunny Thunder Punch vs. 228 HP / 0 Def Azumarill: 204-242 (51.2 - 60.8%) -- guaranteed 2HKO
252 Atk Lopunny Return vs. 228 HP / 0 Def Azumarill: 208-246 (52.2 - 61.8%) -- guaranteed 2HKO
252 Atk Lopunny Thunder Punch vs. 248 HP / 116 Def Mega Scizor: 58-69 (16.9 - 20.1%) -- possible 5HKO
252 Atk Lopunny High Jump Kick vs. 248 HP / 116 Def Mega Scizor: 151-178 (44 - 51.8%) -- 13.3% chance to 2HKO
High Jump Kick also outdamages Thunder and Fire Punch vs. Skarmory:
252 Atk Lopunny Thunder Punch vs. 252 HP / 252+ Def Skarmory: 98-116 (29.3 - 34.7%) -- 100% chance to 4HKO after Leftovers recovery
252 Atk Lopunny Fire Punch vs. 252 HP / 252+ Def Skarmory: 98-116 (29.3 - 34.7%) -- 100% chance to 4HKO after Leftovers recovery
252 Atk Lopunny High Jump Kick vs. 252 HP / 252+ Def Skarmory: 126-148 (37.7 - 44.3%) -- guaranteed 3HKO after Leftovers recovery
Fire Punch is only useful on Scizor and that's it; High Jump Kick still chunks it decently. Ferrothorn is also hit harder by High Jump Kick:
252 Atk Lopunny High Jump Kick vs. 252 HP / 88+ Def Ferrothorn: 296-350 (84 - 99.4%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Lopunny Fire Punch vs. 252 HP / 88+ Def Ferrothorn: 228-272 (64.7 - 77.2%) -- guaranteed 2HKO after Leftovers recovery
Seriously, all Mega Lopunny needs as main attacking options are Return and High Jump Kick.
The only elemental punch Mega Lopunny should consider (it's optional) is Ice Punch because Therian Landorus and Gliscor are rather prominent.