there is no such sensor in pokemon.
it does not evolve
Oddish will evolve at Level 21.
In Pokémon Sapphire, Whismur willl evolve once it reacches Level 20.
Level 34.
Level 38.
level 27
level 18
Level 25.
Level 35.
Level 36.
Level 36.
It will evolve at level 36.