Question

Are you able to see Ferrothorn anywhere in-game without training one?

Answer 1

Actually No, The only way is to catch a Ferroseed, Or request one over the Gts, and then Train it into a Ferrothorn, Although its not that hard.

Just catch a Ferroseed and Experience Share train it to Level 40 for Quick results if you're trying to compltete your Pokedex.

Comments

like EJ-98 said you can see ferroseed, who is found in the Chargestone cave.