it doesn't the stages are azurill marill azumarill
Evolve Marill @ level 18.
Azumarill doesn't evolve according to level in Pokémon HeartGold because it's not capable of evolving at all.
Marill evolves into Azumarill at level 18.
Marill evolves into azumarill at level 18
Marill evolves into Azumarill at level 18.
Marill evolves into Azumarill at Lv 18.
On Pokemon Platinum and Diamond versions, Marill evovles at level 21 into Azumarill. I'm not sure what level on Pearl.I know because I have both versions. :)
it will evolve at level 21
It will evolve at level 48
A Level 25 Marill can still evolve into Azumarill even despite the fact that Marill evolves into Azumarill at Level 18, all you have to do is level it up and it'll evolve into Azumarill as long as it isn't holding an Everstone.
Marill evolves into Azumarill at level 18.
Marill evolves into Azumarill at level 18.