Delphox @ Choice Specs/ Life Orb
EVs: 252 Sp. Atk, 252 Speed, 4 HP
-Grass Knot/ HP Grass
Shame that Delphox doesn't get a good hidden ability like Greninja does, but its got some pretty decent stats, and slightly better defences than Greninja.
Grass Knot & HP Grass depend on a few things, mainly just the tier Delphox is in. I don't think that Delphox will be higher than UU, and considering that Grass Knot is most effective in the higher tiers, especially Ubers because everything there is obese, HP Grass might be your better bet in order to deal consistent damage. I'm pretty sure HP Grass will OHKO Rhyperior anyway.