Rate my team

Just need some help with the items, but here is my White team. (In no particular order)

Venusaur
Nature: Calm
EVs: 252 SpDf/ 252 Spd/ 4 Hp
Moves: Toxic, Substitute, Giga Drain, Leech Seed

Volcarona
Nature: Modest
EVs: 252 SpAtk/ 252 SpDf/ 4 Spd
Moves: Quiver Dance, Fiery Dance, Sunny Day, Substitute

Metagross
Nature: Relaxed
EVs: 252 Atk/ 252 Df/ 4 SpAtk
Moves: Psychic, Hammer Arm, Meteor Mash, Earthquake

Hydreigon
Nature: Brave
EVs: 252 Atk/ 252 SpAtk/ 4 Spd
Moves: Hyper Beam, Flamethrower, Earthquake, Outrage

Braviary
Nature: Adamant
EVs: 252 Atk/ 252 Spd/ 4 Df
Moves: Return, Brave Bird, Rock Slide, Superpower

Swampert
Nature: Brave
EVs: 252 Atk/ 252 SpAtk/ 4 SpDf
Moves: Surf, Hammer Arm, Earthquake, Ice Beam

Hope they are good

Noice team bro! I'd use a choice band on metagross, mystic water on swampert, sharp beak on braviary, charcoal on volcarona, focus band on hydregion, and maybe a grass gem on venusaur?

Venusaur is better suited for Sun teams because of its Chlorophyll (DW) ability; it's seriously mediocre outside of that. Ferrothorn should be in there instead, because of its good defensive typing and bulk:
-Spikes/Stealth Rock
-Leech Seed
-Power Whip/Protect
-Gyro Ball/Thunder Wave/Protect
Nature: Relaxed
EVs: 252 HP/88 Def/168 SDef
Item: Leftovers

Currently, Volcarona is seriously lacking in coverage. If you're using Substitute, you might as well as use Bug Buzz instead of Sunny Day to give Volcarona another STAB to work with. And move the Special Defense EVs to Speed so Volcarona is still fast even before it sets up QD. Timid would be a better nature to use. Give it Leftovers or Life Orb

Metagross can make use of Agility to fix its average Speed; this also makes it a late-game sweeper:
-Agility
-Meteor Mash
-Earthquake
-Zen Headbutt/ThunderPunch/Ice Punch
Nature: Jolly/Adamant
EVs: 52 HP/252 Atk/204 Spe
Item: Life Orb/Lum Berry/Air Balloon

Hydreigon's Speed is decent, even though it's not exactly the best, and a Brave nature wastes that away. And if you want to make it mixed, here's the best set to do that:
-Draco Meteor
-Earthquake
-Fire Blast
-Outrage/Crunch
Nature: Hasty/Naive
EVs: 104 Atk/240 SAtk/164 Spe
Item: Life Orb/Expert Belt

Braviary doesn't do well in OU because of its middling Speed, coupled with a Stealth Rock weakness and lack of recovery (until B2/W2 rolls around). If you can access the Dream World, Gliscor would be a better alternative because of Poison Heal and high Defense:
-Substitute
-Protect
-Earthquake
-Toxic/Taunt/Ice Fang
Nature: Impish
EVs: 252 HP/184 Def/72 Spe
Item: Toxic Orb
Ability: Poison Heal

or
-Swords Dance
-Earthquake
-Ice Fang/Facade
-Taunt/Protect
Nature: Impish
EVs: 252 HP/184 Def/72 Spe
Item: Toxic Orb
Ability: Poison Heal

or
-Toxic
-Earthquake
-Taunt/Ice Fang/Facade
-Protect
Nature: Impish
EVs: 252 HP/184 Def/72 Spe
Item: Toxic Orb
Ability: Poison Heal

If you want to keep Braviary, give it a Choice Band or Choice Scarf

Swampert's physical move pool is decent enough for Choice Band:
-Waterfall/Aqua Tail
-Earthquake
-Ice Punch/Stone Edge
-Superpower/Hammer Arm
Nature: Adamant
EVs: 172 HP/252 Atk/84 Spe
Item: Choice Band

Venasaur should have Red Card because it is slow, has a chance of making opponent switch into a slower Pokemon, disrupt opponent's plan, and you can put up a Substitute.With Hydreigon I think it should have Metronome (item) since it knows Outrage.It can rampage while increasing attack at the same time.The other Pokemon I think you should have at least 1 support/protect/non attacking advantage move because if your Pokemon is only for attacking then the opponent can set a strategy to manipulate your attacks and you would be screwed.Sorry but I can't think of more items for the other Pokemon because of their movesets.