it can only evolve through stones.
it may evolve into a Poliwrath with a water stone (get from Bill's father after showing him Staryu at Cerulean city), or a Politoad using King's rock (you get it from some guy at Mt. moon after you surf and find him)
It evolves into a Polywhirl at Level 25, and then to a Polywrath when given a water stone.
In pokemon crystal Pigeotto evolve in 36lvl
Mareep will evolve at Level 15 in Pokémon Crystal.
Slowpoke will evolve at Level 37.
level 30
The Level When You Get A Life.
30
41
Level 30.
level up a poliwag
Level 36.
You need to level Zubat up to level 22. Then it will evolve into Golbat.