You have three options OP, and here they are:
#1: Special Greninja (the most common one)
Nature: Timid
EVs: 252 SpA / 252 Spe / 4 HP
-Surf / Hydro Pump
-Ice Beam
-Dark Pulse
-Extrasensory / Grass Knot / Hidden Power
#2: Special turning Greninja
Nature: Hasty
EVs: 252 Spe / 252 SpA / 4 Atk
-Surf / Hydro Pump
-Ice Beam
-Dark Pulse / Grass Knot / Extrasensory / Hidden Power
-U-turn
#3: Physical Greninja (regarded by most as a gimmick, not common)
Nature: Jolly
EVs: 252 Spe / 252 Atk / 4 HP
-Shadow Sneak
-U-turn
-Water Shuriken / Waterfall
-Night Slash / Acrobatics
For every Greninja:
-Ability: Protean
-Held item: Life Orb
