Beldum

Beldum is a Pokémon of the Steel/Psychic type. Beldum, just like Magikarp, is a Pokémon with a pre-specified set of moves - in this case, Take Down. Also just like Magikarp, at level 20 it evolves into a form capable of learning a normal ammount of moves. As Beldum can't (currently) be bred, there is only one way to get it: after beating the Elite Four, return to Mossdeep city. On the table in Steven's house is a Pokeball containing a level 5 Beldum. It evolves into Metang at level 20, which evolves into Metagross at level 45. It has a little red eye.

Beldum is a tiny genderless Pokemon, and its evolved forms are also genderless. As Ditto is currently unavailable in Ruby/Sapphire, it's currently impossible to breed a Beldum without use of a cheating device, such as a Gameshark.

Beldum hasn't appeared yet in the anime.