You may be looking for his Prime Zone counterpart.
This is an alternate version of Splash the Greninja that lived in the Dark Mobius universe, making a brief appearance in the Prologue of Secrets of the Dark World: Conquest, and being mentioned in Secrets of the Dark World: Part 1. He was the former leader of the Megastone Rogues before the destruction of the Storming Base, after which he went missing.
Splash most likely retains his appearance.
Splash most likely retains his personality, but due to only having one physical appearance in the Secrets of the Dark World subseries, it hasn't been confirmed.
Splash's past is most likely the same as his Prime Zone counterpart's. The point of divergence is when Knuckles became maddened by his Chaos powers and became Dark Enerjak.
Secrets of the Dark World:
Conquest: Splash appears in the Prologue. When Fox and Knuckles are coming close to blows in their argument, Splash splits them apart, practically snarling that their argument isn't helping anyone. Later, when Knuckles attacks the Base, Splash goes missing along with a large amount of the Storming Alliance.
Part 1: Splash is mentioned to have left after Fox's death.
Splash's moveset was never confirmed, but one confirmed move he has is Water Shuriken.
Splash's Ability is unconfirmed.
Splash's skills are unconfirmed.
As with all Pokemon of his Type(Water and Dark), Splash is weak to Electric, Bug, Fairy, and Fighting. He resists Fire, Ice, Steel, Dark, and Water, and is immune to Psychic altogether.
In Secrets of the Dark World: Part 1, it is mentioned that Splash left following Fox's death, but in Conquest, he disappears during the destruction of the Storming Base.