Use a waterstone on your poliwhirl to evolve it into a poliwrath. However, it is suggested that you wait until your poliwhirl is level 53 to evolve it because that's when it learns its last move. Your poliwrath will not learn Mind Reader or Dynamic Punch by level, but those moves can still be remembered at the move tutor.
I know poliwhirl will evolve to poliwrath and that shelder will evole to cloyster with the waterstone
Poliwhirl to Poliwrath Shellder to Cloyster Staryu to Starmie Eevee to Vaporeon Lombre to Ludicolo
When you give the poliwhirl a water stone
Poliwhirl will evolve into Poliwrath once a Water Stone is used on it. However, Poliwhirl has another evolution called Politoed which is obtained by trading a Poliwhirl while it is holding King's Rock.
you can catch a poliwag and evolve it into poliwhirl, and then use a water stone to evolve the poliwhirl into a poliwrath
you can get a poliwhirl or a poliwag and evolve to poliwhirl!! then trade poliwhirl holding a king's rock.
you must trade with gold or silver in order for poliwhirl to evolve. kings rock
Level 45
Trade with water stone
a water stone makes certain Pokemon evolve like these: eevee-vaporeon staryu-starmie shellder-cloyster lombre-ludicolo panpour-simipour poliwhirl-poliwrath
trade poliwhirl holding king rock item
Poliwag evolves into Poliwhirl at level 20. if you want a Poliwrath use a water stone on your Poliwhirl but if you want a Politoed give your Poliwhirl a King's Rock and trade it.