Pokemon Indigo is a hack of Red, Blue, Green, and Yellow. Therefore, Hoenn Pokemon cannot be caught.
It evolves at level 36
In Pokemon SoulSilver, Marshtomp evolves into Swampert at level 36. See the link below.
Marshtomp
Marshtomp evolves into Swampert starting at level 36.
Marshtomp is #259 in the national pokedex, and it is a Water-Ground type Pokemon.
marshtomp
you cant. if you really want one then start again and get mudkip as your starter pokemon. evole it at LV 16 than you will have a marshtomp
Pokemon indigo does not exist
LV:36
Pokemon indigo is a fake
theres a pokemon indigo?\!
Mudkip evolves into Marshtomp starting at level 16, and then Marshtomp evolves into Swampert starting at level 36. Mudkip is #258 in the National Pokedex, and was introduced in the Generation III Pokemon titles (Ruby, Sapphire, and Emerald) where it was one of the starter pokemon. In Generation VI (X and Y), it is unobtainable by encounter. To obtain this pokemon, you must use the Poke Transporter to move it from another game, or trade for it with another pokemon player, since other people have them and breed them.