Marius (Japanese: ヨウスケ Yōsuke) is the character of the day in The Spheal of Approval.

Marius made himself the self-appointed security guard of the Oceanic Museum. He became angry with Max for trying to get into the museum when it was closed. He believed that him and Ash were thieves so he sent his Spheal out to attack them. Fortunately for them, but unfortunately for Marius, Spheal wasn't interested in battling and only wanted to play. When it finally listened to what Marius said and attacked, it got zapped by Pikachu's Thunderbolt. Marius was in utter shock think that it was impossible for a Pikachu to beat Spheal. Max goes on to explain that Water-types are weak against Electric-type moves.

Soon Captain Stern enters the scene and Marius tells him that Ash and Max were thieves. Max then explains that he just wanted to see the museum. Afterwards, Captain Stern invited them all in to see the museum.

Marius displayed his lack of knowledge about Pokémon whilst in the museum. He said he wanted to catch a Goldeen so that he could "evolve it to Gyarados". Ash then corrects him saying that only Magikarp evolve into Gyarados. Marius also dreamed about traveling around the world by sea inside the submarine that the captain was building.

Soon he, Ash, and Max, are captured by Team Rocket, and then they come to find out that Team Magma stole the meteorite that Captain Stern was going to study. Marius tries to use his Spheal to save them but again it won't listen to him.

After they chase down Team Magma, Captain Stern tells Marius and Max to go back to town to get Officer Jenny. They were able to get there in no time because of Spheal's incredible speed in the water. Later on, they find out that Team Magma got away with the meteorite. Thankfully, Captain Stern did have a small piece of it left. Marius told Ash that he wanted to have a rematch with him the next time they met.

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