No.
Rhydon, in Pokemon FR/LG, does not evolve.
..........level rhyhorn to 42.....get a rhyhorn from safari and evolve it to rhydon
Rhydon at Lv 42.
Rhydon will not evolve in leafgreen or firered you have to migrate it to diamond, pearl or platinum then trade it to evolve it.
You can catch one in the Safari Zone and Cerulean Cave.
In indigo, you don't need hold items to evolve them through trade. Just trade a Rhydon. Your welcome :P
Rhydon doesn't evolve by level. When the Protector is attached to Rhydon, trade it and it will evolve to Rhyperior.
Rhydon evolves into... RHYPERIOR!!
Rhydon evolves into, ---------{rypherior}
Rhyhorn evolves into Rhydon at Level 42. Rhydon can then evolve by attaching a Protector to it and then trading it.
Rhydon is not able to evolve in FireRed.
Rhydon evolves when you trade it while holding a protector.