5th Gen White Treehollow team help

Hi guys I'm just starting the white treehollow and I need help making a team. The team I was thinking was:

Gardevoir: Calm Mind
Thunderbolt
Psychic
Hypnosis

Hydreigon: Crunch
Earthquake
Dragon Pulse
Tri Attack

Carracosta: Rock Slide
Ice Beam
Surf
Waterfall

Skarmory: Spikes
Steel Wing
Air Slash
Fly

Mienshao: Aura Sphere
Fake Out
U-Turn
Acrobatics

Volcarona: Quiver Dance
Flamethrower
Bug Buzz
Heat Wave

Tell me if I should change anyone and possibly item recommendations if you can.

In White Treehollow/Black Tower, there's no level restrictions so simply being of a high enough level will do a lot for you, and you can even use the facility itself to grind levels and money.

Hydreigon has a lot of moves to play around with in B2W2, as it also gets good stuff like Surf, Focus Blast, Superpower, Flamethrower/Fire Blast, Dark Pulse, etc. Depends on what your Hydreigon's nature is a bit, but you can replace Tri Attack with one of those. Skarmory's Sp.Attack is pretty pitiful, and it's a bit more defensively inclined, so replacing Air Slash with Roost via move tutors is a good idea. Aura Sphere is cool, but Mienshao is more of a physical attacker, so you have better Fighting alternatives like Drain Punch or High Jump Kick to consider. Heat Wave is kind of redundant on Volcarona with Flamethrower (in single battles anyway), so I'd drop Heat Wave for some other coverage move, like Psychic or Giga Drain.

As for items....idk. Wide Lens helps Gardevoir's Hypnosis be a little less inaccurate, Skarmory would probably like Leftovers. Berries to weaken super-effective damage are sometimes nice on some Pokemon. Meinshao should go itemless (or use a Flying Gem) since it has Acrobatics though.