Master Splash is a Super Transformation undertaken by Splash the Greninja, though only in times of dire need. Like Fire Fox and Super Spike, Splash can activate this form at will and use it when he needs. Splash first activated this form in The Lost Fox to combat Feral Fox while the latter was controlled by Finitevus' second attempt at using his strange hex that he previously used to control Knuckles, after Feral Fox used Thunder Punch on Austin, badly injuring him. This form is based heavily off of the Ash-Greninja form from the popular Pokemon series. He also has an upgraded form called Master Splash Blade Form; he has undergone this only once so far.
Base Form: Being based heavily off of Ash-Greninja, Splash resembles this form greatly. He retains his base appearance, gaining orange crests on the sides of his face(instead of black and red), the middle crest on his face becomes orange, and he gains an orange crest on each elbow that has two round edges(the inner one shorter than the outer one). He also gains a giant four-point shuriken on his back that he can use for various means as well as using it whenever he uses an attack. When using Cut, he can split the Shuriken into two swords for the attack.
Blade Form: Splash retains his Master Splash base appearance, but the Shuriken disappears, with long, large, sharp blades run down his back, and the middle crest on his face becomes longer and turns watery-blue.
Splash retains his personality.
The Lost Fox: Splash first undergoes this transformation toward the end of the story. Braveheart leads the Alliance patrol and the Chaotix over to fight Finitevus, the Destructix, and a controlled Feral Fox. Austin leaps in front of Splash to take a Thunder Punch meant for the Greninja leader, and is badly injured by it, being knocked unconscious. Enraged, Splash draws power from the nearby Master Emerald(somewhat mirroring Sonic's transformation into Super Sonic at the end of Archie Sonic the Hedgehog Issue 183, since he was unaffected), and becomes Master Splash for the first time. He then battles Feral Fox until the latter regains control of himself and turns on Finitevus. Splash chases after the mad doctor and encounters him trying to escape through a Warp Ring. Splash attacks, but Finitevus knocks him away, coldly stating that he's not finished with the Alliance, bidding the Greninja a mocking farewell before leaving. Angry, Splash reverts to normal and returns to his Teammates.
Raging Storm: Splash activates this form to help Longmire, Wilder, and Shane to capture Scourge during the first Storming Revolt. Scourge escapes-killing Shane in the process-and heads over to where Finitevus is being confronted by Braveheart the Fox and Bushel the Torterra. Splash races after him, now in his Blade Form. After Braveheart is injured and the Storming Revolt fails, Splash reverts to normal. During the second Storming Revolt, Splash is once more in Master Splash form. When Fox defeats Finitevus, the mad Echidna escapes through a Warp Ring, but Splash chases after him without a second thought.
Struggle Against the Shadows: In the Prologue, Splash is in his Master Splash form, facing down a surprised Finitevus. A short fight ensues, ending with Splash being shoved through another Warp Ring, into the Land of Shadows.
Splash's moveset is the same as it was, but he can use all attacks learnable by all Pokemon. He commonly uses his Shuriken in these attacks.
While Splash's regular Ability is Torrent, its possible that his Ability as Master Splash is Battle Bond.
Same as his base form.
Same as his base form. Master Splash also can use Aura, and this means he can sense other people's emotions, and even their pain(since during Raging Storm, Splash was hindered when Braveheart was injured).