Well, having 2 moves of the same type is a big no no, as it restricts the potential of the Pokemon. Both Sheer Cold and Icy Wind aren't the greatest of moves, because Sheer Cold misses nearly half the time, and Icy Wind does minimalistic amounts of damage. Teach it Ice Beam, via the Move Relearner (one of the best moves in the game). Likewise, haviong 2 Flying moves restricts the potential... so get rid of Peck, which also does minimalistic damage, but keep Wing Attack (although if you trade onto RuSa, you could replace it with Aerial Ace). For the other two moves, it's best to post what EVs you want to have it, although I do suggest Reflect (to boost its lackluster Defense) and something like Water Pulse, to fight Fire and Rock Pokemon. Here's the set again:
Ice Beam
Wing Attack/Aerial Ace
Reflect
Water Pulse
Also, Type boosting items never work in the way people think they do. Leftovers are the best, although if you can't get them - the Shell Bell should work fine.
~ MCD