Mega-Scizor:
No problems.
Greninja-Ash:
It looks fine.
Tapu Koko
Tapu Koko would function much better as an offensive pivot. Keep the U-turn and Volt Switch, but replace your Life Orb with a Magnet. This way, Thunderbolt hits even harder and you don't have to waste your HP. Tapu Koko is also much too frail to switch in on most things, so save it for revenge killing.
Tapu Fini
Tapu Fini is actually an excellent Defogger. A better set would maybe be a defensive Tapu Fini, with a Calm Nature and Taunt, Nature's Madness, Moonblast, and Defog. This would allow it to shut down many leads, such as Chansey and Skarmory, who rely on status and entry hazards.
Mamoswine
Mamoswine is a decent wallbreaker, but I would recommend Thick Fat over Oblivious, as Taunt has no effect anyway.
However, if you want a better wallbreaker, I recommend this set:
Pheromosa @ Focus Sash
Ability: Beast Boost
EVs: 224 SpA / 32 SpD / 252 Spe
Modest Nature
- Quiver Dance
- Bug Buzz
- Focus Blast
- Ice Beam
Machamp
Machamp is in RU. Rarely Used. That's two tiers below OU. Why would you use Machamp? Almost any pokemon would be better than Machamp. You could use Landorus-Therian, for example.
Landorus-Therian @ Life Orb
Ability: Intimidate
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Earthquake
- Swords Dance
- Stone Edge
- Stealth Rock