You can evolve Shroomish by leveling it up to level 23, which can be done by battling with it until it gains enough experience to level up.
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or you could give it exp. share which is found when u help the mayor in penac city then u talk to him and he will give it to u.
he evolves into mightyena at level 18
Zubat evolves at Level 22 in Pokémon XD.
it evolves in lvl 18...xD
at levl 30
Flaaffy evolves at level 30.
the amazing swinub evolves at level 32,33,or,34
Pupitar evolves at Lv 55.
Houndour evolves at level 28
Larvitar evolves at Level 30 in Pokémon XD.
Numel evolves into Camerupt at level 33
Spinarak evolves into ariados at level 22.
"technically" it evolves at level 20 on all Pokemon games, but since you catch it at level 22 on Pokemon xd, it should evolve at the next level up after purifying it.