you have to go on the ss anne and find the captin rub his back and he will give it to you
Rhydon, in Pokemon FR/LG, does not evolve.
You must trade it over from FR/LG.
Since it's a Kanto Pokemon, it must be traded from FR/LG.
Professor Oak's assitant will give it to you. Oak's assistant WON'T give it to you. He does that in RBY/FR/LG. In Pokemon Gold, Silver, Crystal, HeartGold and SoulSilver, the Elder in Sprout Tower will give it to you. In GSC, Flash is a HM, in HG/SS it is a TM.
R/S/E: Trade from FR/LG FR/LG: Evolve water starter D/P/Pt: Trade from FR/LG HG/SS: Evolve Kanto water starter