A Lombre can only evolve into Ludicolo if you use a Water Stone. If you don't use one, you'll just get a very powerful Lombre.
It does not evolve at a certain level. You need a water stone
it evolves at level 14, you use a water stone to evole lombre in to ludicolo
level 40
Level 30.
Level 32.
On level 20.
level 26 ^^
at level 32
At level 59
Level 16.
Level 16
Lombre is one of the pokemon that do not evolve by level he evolves by using a water stone.