1. That's a Big Mouse-Yama discovers a wig that can turn him into the powerful Sumo Mouse when his uncle is kidnapped by Claw.
2. That's a Lot of Missing Sumos-Sumo wrestlers have been disappearing and Sumo Mouse must find out why.
3. That's a Nasty Lizard-Claw attacks Catropolis with a robot dinosaur
4. That's a Big Butt-Claw frames Sumo Mouse for destroying several historical sites.
5. That's a Really Ancient Scroll-Yama and friends try to get an old scroll to learn more about Sumo Mouse but Claw is trying to get it as well.
6. That's a Smelly Cheese-Claw discovers an ancient cheese capable of weakening Sumo Mouse but a new villain named Morpho Mouse wants it as well
7. That's a Bizarro Sumo-In order to help with crimefighting, Wazzie clones Sumo Mouse but the clone is evil.
8. That's a Wise Mouse-Sumo Mouse come under the tutelage of an old Master who plans to get Sumo Mouse to tell him his secret identity.
9. That's a Nice Kitty-A new hero, Catrobat, arrives in Catropolis.
10. That's a Bit Chilly-Sumo Mouse tries to find his way through the snowy caves of Mt. Sumo while Claw's henchmen accidentally freeze Catropolis.
11. That's a Close Shave-Aunt Dot is kidnapped by Claw to be his personal stylist.
12. That's a Cunning Plan-While working on a hypnosis machine, Claw accidentally hypnotizes Vinnie into becoming a genius.
13. That's a Big Secret-Claw weakens Sumo Mouse with darts poisoned by the big cheese while Nadia tries to learn Sumo Mouse's secret identity from Wazzie.
14. That's a Super Kitten-After his falling out with Yama, Wazzie tries to strike it out as a hero on his own.
15. That's a Scaredy Mouse-Yama tries to undergo several trials to see if he's worthy of the wig but is zapped by Claw's fear ray.
16. That's a Bunch O' Bugs-Yama creates a fake scroll to mislead Claw while Claw unleashes self-replicating robot bugs in the caves.
17. That's a Bad Prince-After putting on an ancient amulet, Twitch is possessed by the spirit of the evil Prince Tut-Tut-Matata-Hah.
18. That's a Yummy Sandwich-Claw frames Tabby for killing his goons.
19. That's a Sidekick in the Pants-Catrobat (now Catrobot) is called back to Catropolis by Claw to fight Sumo Mouse. Meanwhile, Wazzie's dad discovers that he's Kamikaze Kitten.
20. That's a Crazy Code-Wazzie and Tabby make a bet to see who can crack the ancient sumo monks' code first while Nadia spies on them for it.
21. That's a Spooky Phantom-The Sumodome is haunted by a ghost, much to the fear of Yama and Sumo Mouse.
22. That's a Great, Great Uncle-A spell book belonging to Claw's ancestor is discovered and Claw forces Tabby to translate it.
23. That's a Tiger Tamed-While investigating berserker sumos, Sumo Mouse discovers that Tabby's father Tiger is working for Claw.
24. That's a Cosmic Calamity-Claw moves the planet out of alignment to strip Sumo Mouse of his powers. To further complicate things, Nadia turns him good.
25. That's a Team of Terror-Ritzoid, Satanori, Morpho Mouse and Catrobot are formed into Team Terror by Claw to get Sumo Mouse.
26. That's a Cataclysmic Decision-Yama has finally found Uncle Herbie but Claw has also found the big cheese motherlode! Sumo Mouse's friends must revive him before Claw destroys Catropolis.
