This is my current team. Please comment and give feedback. I also might want to change some of their nicknames, so any suggestion on that is also greatly appreciated.

Okay, I'm not an offical rater, but since it's not in the offical rating thread, I'll rate it anyways.

(Meanie) @ Metronome
Timid nature (+ Spd, - Atk)
252 SpAtk, 252 Spd, 6 HP
Surf
Sludge Bomb
Toxic Spikes
Barrier

I lead out with this Pokémon so I can spread Toxic Spikes and so its power isn't lowered by the Sunny Day. I also set up a Barrier and then attack with Surf and Sludge Bomb until I faint.

Good, I like how you use this as a support pokemon with barrier, and a spiker too. Since your team has weakness to types that have mostly special attacks, I might change barrier to light screen.

(Flora) @ Heat Rock
Quirky nature (balanced)
252 SpAtk, 252 Spd, 6 HP
Magical Leaf
Sunny Day
Solarbeam
Toxic

With , I use Sunny Day, which powers up my team because of its ability Flower Gift. I can then use Solarbeam every turn, or Magical Leaf if I am against an Evasive foe.I use Toxic on Flying types or Pokémon with Levitate who are not affected by Toxic Spikes.

Good, I like how you have a back up pokemon for tentacruel. No corrections for this pokemon.

(Flames) @ Expert Belt
Hasty nature (+ Spd, - Def)
252 Atk, 252 Spd, 6 HP
Earthquake
Blaze Kick
Sky Uppercut
Bulk Up

I can use Bulk Up to raise my Attack and Defense, then with 's Flower Gift still in affect, I can use my damaging moves, especially Blaze Kick, for it is powered up in sunny weather.

Okay, I might replace sky uppercut with a special move like flamethrower, becuse no one uses Hm moves except for surf, and except for earthquake your offensive moves have somewhat low accuracy. A good choice, though. THis is a pokemon that can turn a battle around.

(Wise One) @ Quick Claw
Bashful nature (balanced)
252 Atk, 252 SpAtk, 6 HP
Energy Ball
Rock Slide
Stockpile
Confuse Ray

What I usually do with is I confuse them with Confuse Ray, then I use Stockpile 3 times. Stockpile raises Defense and Special Defense. I then attack with Energy Ball and Rock Slide.

Okay, I think you should change stockpile to another defensive move that raises your defensive stats more. It doesn't have to raise both of them.
Or, you could change energy ball and rock slide to swallow and spit up.

(Magnetic) @ Wise Glasses
Quirky nature (balanced)
252 SpAtk, 129 Def, 129 SpDef
Thunder Wave
Discharge
Flash Cannon
Magnet Rise

First I use Magnet Rise if I think they have ground type moves, then I paralyze them with Thunder Wave. I then attack them with Flash Cannon and Discharge.

Magnezone isn't the best pokemon, but I think your moveset makes it okay. You may want to change this pokemon with a special sweeper in the future.

(Beeg Bug) @ Focus Sash
Hasty nature (+ Spd, - Def)
252 SpAtk, 252 Spd, 6 HP
AncientPower
Bug Buzz
Double Team
Air Slash

I decide if I can KO the opponent in one hit. If I can, I do so with my moves. If not, I raise my Evaison and then I attack.

Okay, good. It wouldn't have any 1-hit KOs against my pokemon, but if it can use double team enough, it can be a real problem for opponets.

Well, I hope you will give me feedback so I can continue to make this team better and better!