• English / United States: Sanpei's Greninja
• Japanese / Japan: サンペイのゲッコウガ
• Japanese (Romanized) / Japan: Sanpei no Gekkouga
• Japanese (TL) / Japan: Sanpei's Gekkouga

Sanpei's Greninja is the evolved form of Sanpei's Frogadier. It evolved during the time that Sanpei first met Ash Ketchum and the time he was being tested by Saizo.

Saizo had a task for Sanpei and Sanpei's Greninja and he asked them to take a secret document containing ninja techniques that have been taught in their ninja village since olden times and deliver it to their allies. During a battle between Saizo's Barbaracle, which at the time was the masked ninja's Pokémon, Sanpei's Greninja was poisoned. After Sanpei and Sanpei's Greninja safely finished the mission and Saizo revealed himself as the masked ninja, he told Sanpei that he would report back to their elder about how well they performed together. Sanpei's Greninja didn't realize that masked ninja was Saizo and it had a very surprised look on its face when he was revealed.

Battle vs Nihei's Venusaur

When Sanpei returned to visit the ninja village, Nihei's Venusaur had a battle against Sanpei's Greninja to show his brothers the results of his studies right away. Nihei also said he wouldn't go easy on him.

Hanzo noted that Sanpei's Greninja fighting against Nihei's Venusaur meant that Sanpei had a disadvantage but nonetheless fought on an even level. Although, it wasn't enough to win the battle as Nihei's Venusaur was able to contain the damage to a minimum and waited for a chance to turn the tables.