rhydon will only evolve if you make it hold protector and trade it.
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 have to evolve a ryhorn from the safari zone
To evolve rhydon you must equip it with the protector and trade it, and probably get it back.
You must have a protector which is located in Route 228, you must first evolve Ryhorn to Ryhdon at lvl 42 then give Ryhdon the protector to hold and then trade it with someone, trade it back and you'll get Ryperior.
it depends on levels
To evolve rhydon you must give it the protector and trade it ( if you want it trade it back)
It is suppose to evolve at the Level of 20,but if you want it to evolve later it can evolve anything after it is at Level 20.
He doesn't you need to give them a protector them trade them. Several other Pokemon evolve this way. Check out: http://bulbapedia.bulbagarden.net/wiki/Protector#Protector There is a list.
It will evolve by level. Teddiursa will evolve into a Ursaring at level 30.
They evolve at level 36
It will evolve at level 36.