At mistralton cave at level 30 or 31 (you need surf to get to the cave)
You cannot catch a Rhydon in Black and White. You have to catch a Rhyhorn and level it up to level 42. Rhyhorn is only available in Pokemon White in White Forest.
You can't catch rhydon in Pokemon white. You wil need to evolve an rhyhorn at level 42 which you can catch in white Forrest.
10
100
you catch a deino at victory road an level it up to level 64
it evolves at level 36 and you can catch Crustle at route 18
You can find Rayquaza which is a legendary Pokemon at lvl 70. There are other Pokemon arround lvl 35 in the victory road. Rayquaza is on the last floor of the Sky Tower and is a little tricky to catch because he uses rest that fully restores his HP. But you can use moves like Hypnosis and Sleep Powder to make him fall asleep and it will be easier for you to catch Rayquaza while he is asleep.
Catch Tynamo at Chargestone Cave, then train it until it reaches level 39.
Forget axew! You can catch a level 40 fraxure in victory road!
if you hack your game you can encounter a level 100 ho-oh
You cannot catch Hydreigon on Pokemon White.
you can not catch graveler on Pokemon white Sorry:):):):)