The ability to ALWAYS since X and Y (And Colleseum and X D) be able to move in eight ways.
Certain moves appear when in effect.
List of itself ^ Will show at bottom
A little bit more of shaders.
When in battle, items are shown either on, or beside the Pokémon. (My favourite addition)
Improved animations (Dropping a fossil from Flareon's mouth, and biting <Pokémon> then running back and taking the 'HELIX' fossil again)
Personally, the Wii U should be able to handle at least one of this, if the 3DS can handle ALL of the models of ALL the Pokémon, including the shinies.
(Also, eight ways has like a 99.9 percent chance of being a thing with the Analog stick on the Wii U)
Moves to be shown specially:
Grassy Terrain: Forms a patch of grass in the battlefield, changing stone, dust, sand, metal, ETC)
Electric Terrain: Forms clouds on the ground, sending bolts dancing around in the background.
Misty Terrain: Creates pink fog to shroud the battlefield.
Stealth Rock: Stones float around the team, then turn inwards when they take damage from it.
Spikes: Spikes, instead of disappearing, stay until they are destroyed. They simply stay on the ground.
Leech Seed: A tiny plant appears either on, or beside the Pokémon that was seeded.
All weather effects are obvious.
What would you guys like?