[RATE MY TEAM] need advice/rate

[rudexdudes]

I'm fairly new to competitive battles and I'd like to think this team is good but I'm not 100%. Any suggestions on how to make the team better is highly appriciated.

Grenada @ Expert belt
Timid Protean
252SpAtk 252Spe 4th Def
Scald
Ice beam
Grass knot
Dark pulse.

Volcarona @ leftovers
Modest Flame body
96HP 252SpAtk 160Sp
Quiver dance
Fire blast
Giga drain
Bug buzz

Mamoswine @ Life Orb
Adamant Thick fat
252Atk 4Def 252Spe
Ice fang
Earthquake
Superpower
Protect

Dragonite @ don't have an item idea.
Adamant Multiscale
4HP 252Atk  252Spe
Roost
Fire punch
Dragon claw
Thunder punch

Gardevoir @ Safety Goggles
Modest Trace
252HP 124Def 108SpA 20SpD 4Spe
Moonblast
Psychic
Wil-o-wish
Taunt

Mega Venasaur
Bold
252HP 240Def 16Spe
Giga drain
Sludge bomb
Synthesis
Sleep powder

Any suggestions on different moves, items, or even different pokemon will help. Thanks.  :D