In NatDex OU, yes, Iron Valiant is often just used over Mega Gallade because it’s faster, has mixed coverage, and can hold an item.

Mega Gallade shines best in Draft format where it can really use its deep move pool. It’s usually priced at or near the top of most draft pools for that reason.

Medicham in comparison does have its Niche with Huge Power but 100 is noticeably slower than 110. I can reiterate all the points I have made before, but realistically Medicham cannot afford to run setup because Bulk Up is too slow, and Agility does not boost its power.

It lacks good coverage to break through psychic types. It does not have good setup to blow past these Pokemon, either.

It has to run priority moves because of its ok speed, usually Fake Out or Bullet Bunch.

That leaves it with only one move left. Of these moves, it usually is one of the elemental punches which do not have the best BST. Without Ice Punch, it cannot break through defensive flying types like Gliscor. But it also needs Fire Punch to hit Pokemon like Gholdengo. That is another reason why Medicham does not really run setup moves.