My Ash-Greninja has:
Ability: Battle Bond (Obviously)
Item: Focus Sash/Leftovers
EVs: 276 Speed, 123 Sp Atk, 234 Attack, 146 Defense, 69 Sp Defense
Moves: Scald, Ice Beam, Dark Pulse, and Grass Knot/Aerial Ace
Scald: Scald is a sweep move. Use it on Ground, Fire, and Rock types and they won't stand a chance. Plus, it can burn the opponents if they don't get one hit KO'd.
Ice Beam: For those darn Dragon types like Garchomp and Salamence who can learn Rock Smash and Noivern who can learn Focus Blast. Use it, and because Greninja's amazing speed, it will 96.98% be likely to go first
Dark Pulse: Dark Pulse is a must have. It can take out Haxorus, a crazy strong Dragon type in one hit. It is, as you know, great for killing Psychic and Ghost types.
Grass Knot/Aerial Ace: Grass Knot is a great move to take out annoying Water, Electric, and Ground types. Aerial Ace is REALLY GOOD for taking out those stupid Fighting types, plus it's super fast.
I REALLY HOPE THIS HELPS YOU AND Hell Fire Taco THANKS FOR THE GRAMMAR POINT OUTS A LOT!!