safari zone
You need to evolve Rhydon. Rhydon evolves when you trade it when it holds a Protector. You find a Protector on Iron Island and Route 228. See related link on details on where to find Rhydon.
on victory road
one is rhyhorn and another is rhydon which rhyhorn evolves at lv. 42 to rhydon
there aren't any trainers who use a Rhydon in Pokemon platinum, but you can see a Rhydon on Route 228 ~ actually there is a trainer in Pokemon platinum who has a Rhydon and he is in victory road. when you are in victory road where you see all the water just go surf on the first one and then land where you see three lakes. once you are there go all the way right and you should see a trainer jogging up and down beside an item. battle him and he has a Rhydon in his party.~ How would people get to route 228 IF THEY WANTED TO FINISH THEIR SINNOH POKEDEX!!
it may be in sinnoh. rhydon can be gotten by evolving your rhyhorn on your gameboy games. first see all 150 Pokemon in sinnoh . talk to rowan. go to pal park. transfer your rhydon (WITHOUT HM MOVES LEARNED!) then u get rhydon.
Rhydon evolves into... RHYPERIOR!!
Rhydon evolves into, ---------{rypherior}
give the rhydon a protector and then trade the rhydon. it will evolve into a rhyperior. then trade it back.
Rhydon doesn't evolve by level. When the Protector is attached to Rhydon, trade it and it will evolve to Rhyperior.
On victory road you find wild Rhydon at about level 40. I don't remember where to find a trainer with one, but you could also battle a friend with one in the union room.
you can only get Rhydon by evolving Rhythorn which can be found in the safari.
you can find a Rhydon on route 226 :)