It evolves to Azumarill at level 18. You just have to level it up to evolve it.
Marril evolves at 23, 18 or 24.
To evolve Marril you have to get it to level 18.
at lvl 18
look up marril in the pokedex then press A. the pokedex could locate marril . if that doesnt work then try the safari zone
Azurill
It is suppose to evolve at the Level of 20,but if you want it to evolve later it can evolve anything after it is at Level 20.
It will evolve by level. Teddiursa will evolve into a Ursaring at level 30.
They evolve at level 36
It will evolve at level 36.
They evolve on level 40
it evolve on level on 64
if you dont let it evolve at the required level of level 20. itll try to evolve at every level following.