How do you get the strength ability in Pokemon FireRed?

If you have a bird Pokemon and teach it fly. then you have to fly to fushia city. If you go into the safari zone you'll fine golden teeth in a poke' ball on the ground. Then you take it to the house to right of the poke'mon center. The slowpoke warden will be in there. If you talk to to him he'll give you strength. Then use it right next to him on the big boulder then press "A" on the poke'ball and then you'd get a rare candy.