If Medicham is going to have a niche over Gallade, it would have to come from its access to Recover. Double priority isn't a great niche, especially since Lopunny and MMeta probably do their one priority better than Medicham does both.
This set has a lot of problems (burns, Talonflame), but I think it carves out a bit of a niche for Medi. Let me know what you guys think:
Medicham @ Medichamite
EVs: 252 HP/4 Atk/252 SpD
Careful Nature
- Bulk Up
- Drain Punch
- Zen Headbutt / Facade
- Recover
Medicham doesn't have great bulk, but with full SpD investment, it can take neutral special attacks pretty well, and proceed to boost and heal with Recover/Drain Punch. A few of the possibilities:
252 SpA Mega Sceptile Giga Drain vs. 252 HP / 252+ SpD Mega Medicham: 108-127 (33.3 - 39.1%) -- guaranteed 3HKO
216 SpA Life Orb Protean Greninja Ice Beam vs. 252 HP / 252+ SpD Mega Medicham: 126-149 (38.8 - 45.9%) -- guaranteed 3HKO
252+ SpA Mega Venusaur Sludge Bomb vs. 252 HP / 252+ SpD Mega Medicham: 124-147 (38.2 - 45.3%) -- guaranteed 3HKO
So, I don't know if this Medicham is viable, but it can at least do something that Gallade can't.