Ralts is Psychic/Fairy type Pokémon. It can learn the 'Thief', which is a Dark and Physical move at level 25. This Pokémon have two evolution options, if male, it evolves into Gallade, if female, it evolves into Gardevoir.
lvl 53
The Pokemon that can learn Thief are listed at this site: http://bulbapedia.bulbagarden.net/wiki/Thief
level it up at night
It can't evolve by level, but it can evolve while holding the item Razor Claw at night. It can only evolve in 4th generation games and above. (Diamond, Pearl, Platinum, HG, SS, etc.)
Level up a Sneasel while it is holding a Razor Claw.
Alakazam, Gengar, KAdabra, sneasel, sandslash and others
lvl 53
sneasel learns it at level 57
Clefable cannot learn thief at any level, not even from the TM. However it may use Thief if it knows Metronome, or a similar move.
Most dark types like sneasel or some psychic types like Abra some normal types like linoone and furret and clefable and wigglytuff can learn thief.
Lotad cannot naturally learn it but it can be taught Thief with a Thief TM. Lotad's evolved form Lombre learns Thief at Lv. 37.
Marshadow learns Spectral Thief at level 45.
lvl 57
Well, starly (or staravia) will eventually learn thief when leveling up. Personally, I I think Thief is a useless move.
Sneasel can only learn ice punch by having a parent, Buneary, that knows the movie. Sneasel cannot learn ice punch through any other method.
A keckleon in the wild already noes thief.
it dosent learn ice beam through leveling up but it does learn icy wind at 28 and ice shard at level 49. It can learn ice beam from a TM.