Team help

I just need some help with my White team. It consist of...

Venusaur
Nature: Calm
EV's: 252 SpDf/ 252 Spd/ 4 Hp
Moves: Toxic, Substitute, Leech Seed, Petal Dance

Swampert
Nature: Brave
EV's: 252 Atk/ 252 SpAtk/ 4 SpDf
Moves: Earthquake, Ice Beam, Muddy Water, Hammer Arm

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

Hydreigon
Nature: Brave
EV's: 252 Atk/ 252 SpAtk/ 4 Spd
Moves: Outrage, Earthquake, Focus Blast, Hyper Beam

Volcarona
Nature: Modest
EV's: 252 SpAtk/ 252 SpDf/ 4 Spd
Moves: Quiver Dance, Fiery Dance, Sunny Day, Solar Beam

Braviary
Nature: Adamant
EV's: 252 Atk/ 252 Spd/ 4 Df
Moves: Brave Bird, Rock Slide, Slash, Superpower

So, how is it?

Sunny Day + Solarbeam is too gimmicky on Volcorona. Go with Bug Buzz for secondary STAB and Substitute, which helps you to set up Quiver Dances.

Return > Slash on Braviary. Sure, the crit-rate on Slash is cool, but Return is more reliable.

Surf > Muddy Water on Swampert. iirc Surf has a higher power and/or accuracy than Muddy Water.

Being locked into a move is annoying for a bulky Pokemon, which is why I think Giga Drain > Petal Dance is good on Venusaur. Plus it allows you to heal yourself further so as to replenish subs.

Flamethrower > Focus Blast on Hydreigon as Flamethrower gets better accuracy and also great coverage alongside Outrage. I'd also go with Crunch > Hyper Beam as Crunch gets STAB, is a powerful move, can pick off Psychic-types easily as they generally have a low defence, and plus Hyper Beam requires a recharge time which is gross.

Sorry for the meh-ish rate, it's been a while since I've rated.