Kinda new to gen 6, and I need advice for a better team

I got:
Gardevoir: Timid > Trace > Gardevoirite > 252spe 252spa 6hp

Calm Mind
Psyshock
Moonblast
Hyper Voice

Cloyster: Jolly > Skill Link > Life Orb > 252atk 252spe 6hp

Rapid Spin
Rock Blast
Icicle Spear
Shell Smash

Rotom: Bold > Levitate > Shed Shell > 248hp 252def 10spe

Volt Switch
Hydro Pump
Will-O-Wisp
Pain Split

Dragonite: Jolly > Multiscale > Assault Vest > 252def 252spe 6spd

Outrage
Earthquake
Extreme Speed
Power-Up Punch

Cresselia: Bold > Levitate > Leftovers > 252hp 252def 6spd

Attract
Ice Beam
Toxic
Moonlight

Aegislash: Relaxed > Stance Change > Red Card > 252hp 252def 6spd

King's Shield
Gyro Ball
Swords Dance
Shadow Sneak

Considering a Victini with 252hp 252spe Choice Scarf and Final Gambit

Give it to me straight /vp/. I don't even care if I've got to use ubers, as long they work better