Mario Stadium is one of the playable stadiums in the Mario Baseball series, appearing in both entries. It is the most basic stadium and happens to be set near the beach. In Mario Super Sluggers' single player mode, it is the first explorable location, teaching the player how to play.
When Mario first enters the Stadium, Luigi greets him and joins Mario's team. A Blue Noki can be found on the eastern end of the beach, if the player beats her batting challenge she will join Mario's team. A Green Noki can be found on the western end of the beach, and will join the Mario's team if he can throw 3 charged pitches. If both Noki's are on Mario's team, then a Red Noki on top of a Sea Shell in the center of the stadium. A blue Magikoopa is hidden inside the sea shell, and will challenge Mario to a pitching challenge.
After Mario defeats the Magikoopa, a switch puzzle will be unlocked (Right, Left, Left, Right, Left) that is used to lower the bridge. The bridge will lower, and Mario can go and talk to Baby Luigi. After Baby Luigi joins Mario's team, Bowser Jr will challenge Mario to a baseball game. Once Mario defeats Boswer Jr, he runs away and leaves behind Baby Mario, and the key to the Sea Hut.
Inside the Sea Hut is Blue Pianta. Blue Pianta will join Mario's team. If the player collects the other Captains they can unlock more characters for the Mario Fireballs. In the Northwest corner of the map there is a collection of barrels, if the player has DK with them, they can use his ability to break the barrels, and inside one of them is a Yellow Pianta, his mission is to lay down a squeeze bunt.
In the middle of the map there is a palm tree, if the player has Yoshi, then they can use Yoshi's ground pound ability to find the Red Pianta, he will challenge you to get the ball with a tongue catch. On the western beach, the player can use Princesse Peach to uncover Monty Mole. Monty Mole will challenge the player to a fielding challenge. The last character on the Mario Fireballs is Blooper. Blooper can be found on the Western dock. If Peach uses her ability to make blooper jump out of the water, then he will challenge the player to a pitching challenge.
There is a treasure chest on an island off the west coast. On the east dock Mario can jump into a warp pipe, which will send him to the island, where he can challenge Dry Bones. If he defeats the Dry Bones, then the player can use Wario to unlock a treasure chest.