- Debuts In: "Let the Show on the Road"
- Caught At: Littleroot Town
- Evolves In:
- Volcanic Panic
- Amigos Fiesta!
- Gender: Unknown
- Ability: Torrent
- Current Location: With Sapphire.
In Let The Show on the Road, Swampert was given to Sapphire by Professor Birch in Littleroot Town when it was still a Mudkip. She chose it as her starter Pokémon because she thought Treecko was creepy and scary (though she later called them cute in Sceptile's Battle), while the starter Torchic had attacked her earlier with a Ember to the face. However, she seemed to like Mudkip's cute appearance and sweet nature. Early on in the journey, Mudkip was very inexperienced and ditzy. It did not know how to battle, and tended to wander around obliviously; it also tended to panic when in dangerous situations. On the group's first encounter with Jessie's Seviper (still wild at the time), the Poison-type frightened Mudkip by trying to eat it.
When Sapphire started to ignore Mudkip in favor of her new Beautifly, Mudkip's personality began to change: it grew more determined to improve itself and recapture Sapphire's attention. Its competitive streak continued to grow as it lost most of its childishness and confusion; this culminated in its evolution into Marshtomp during Volcanic Panic. Marshtomp itself had a period of being highly aggressive, but this seems to have passed and its personality seems to have evened out more now that it apparently feels that it no longer has to overcompensate.
In Amigos Fiesta, during the break of a Pokémon Contest, Ash and co. were trying to stop Team Rocket from stealing Pikachu and other Pokémon. In the midst of the ensuing battle, Marshtomp evolved into Swampert, and used its Focus Punch to send Team Rocket flying, upon which Ash remarked "would I love to battle you". Afterwards, Sapphire used Swampert in the Battle Phase against Ash's Infernape. Although it had a type advantage over Infernape's and its Torrent ability activated at the same time Infernape's Blaze did, the battle ended in a tie. Later, it left for Hoenn with the rest of Sapphire's Pokémon, along with Sapphire went to Sinnoh with Ash.
Swaampert appeared again when Sapphire made a guest appearance in Full Courses of Tag Battle.It was used in the Seven Stars Restaurant tag battles, in which it battled alongside May's Blaziken. When it was first called out, Ash seemed to be pleased at seeing it again, and Brock remarked that it had gotten stronger as well.
Swampert used many times in Contest in Sinnoh and Johto by Sapphire.
In BS009, Swampert becomes more jealous of Sapphire Paying attention on Dawn and Ash's Togekiss and Gible instead of Swampert and Swampert learns to use Hyper Beam and Mirror Coat.
In BS013, Swampert becomes jealous of Sapphire's new Pokemon, Absol and fights with him all along which Sapphire returns Absol into the Pokeball.
|Known Moves||First Used|
|Water Gun||A Ruin with a View|
|Tackle||A Ruin with a View|
|Mud Shot||Volcanic Panic|
|Mud Bomb||Volcanic Panic|
|Take Down||Marshtomp Double Trouble|
|Protect||Pokemon Ranger - Deoxys Crisis (part 2)|
|Earthquake||Opening the Battle Zone|
|Hammer Arm||Amigos Fiesta|
|Surf||A Full Courses of Tag Battle|
|Hydro Pump||A Full Courses of Tag Battle|
|Hydro Cannon||A Full Courses of Tag Battle|
|Ice Punch||a Strategy with a Smile|
- Sapphire's Swampert is the only Hoenn starter belonging to a main character that did fall in love with a Fire Type Pokemon is Charmeleon
- As a Mudkip, it was very fond of tasty Passho Berry.
- As a Marshtomp, it has participated in the battles of both Grand Festivals where Sapphire was Win(Melody in the Sky in Hoenn, and Amigos Fiesta in Kanto).
- Both its first battle as a Marshtomp (against the Wild Camerupt) and its first official battle as a Swampert (against Ash's Infernape) resulted in a tie. Notably, in both instances it fought against a Fire-Type Pokémon.
- Marshtomp evolved into Swampert exactly 100 episodes after its first Contest victory (in Fortree City).