What to switch in my team? (Pokemon Y)?

Question

I got some Pokémon I want to use in Y but I don’t know what to replace them with.

My team is:

Garchomp: Hidden Ability
—Earthquake
—Dragon Claw
—Shadow Claw
—Slash

The grass starter fully evolved(I nick named mine so Idk it’s name:
—Spikey Shield
—Brick Break
—Dig
—Vine whip

M-Blastoise:
—Blizzard
—Scald
—Strength
—Dig(I think)

Sliggoo: Hidden Ability. 1 level away from evolving.
—Draco Meteor
—Thubderbolt
—Bubble
—Sludge bomb(or sludge wave, I forgot)

Glaceon:
—Ice beam
—Frost Breath
—Toxic
—Shadow ball

Tyrantrum:
—Hone Claws
—Stealth Rocks
—Dragon Claw
—Earthquake

I got Yveltal and am getting Mewtwo and Zygarde. Problem is, my team already looks so nice, I can’t see any use of replacing and of them.

Edited more stuff.

Comments

Take out 2 of your dragons. Having 3 or 4 dragons is probably not a good idea.

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The Grass starter is called Chesnaught

Answer 1

Take out Tyrantrum, Sliggoo, and Zygarde so you don't have multiple dragon Pokemon stacking weaknesses.

Comments

Well done. What should I replace em /w?

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Probably Yveltal and Mewtwo?

Answer 2

Dude, my suggestions:
1) Garchomp : Try using Swords Dance instead of slash/ Use an (Expert Belt/ Assault Vest/Rocky Helmet) depending on your nature/EVs. Replace with Zygarde when you catch it.
2) Chesnaught : Try using Wood Hammer/Seed Bomb instead of Vine Whip. Replace with Mewtwo because it can learn Energy Ball and Aura Sphere.
3) M-Blastoise : Dont waste its Mega Launcher ability, try using Aura and Pulse moves, just google. Or use Shell Smash sweeper moveset
4) Evolve Sliggoo and use a Specs set for sweep
5) If you wanna keep using Tyrantrum, use Jaw moves to use its Strong Jaw ability, like Crunch, Fang moves etc.
Replace with Yveltal after catching.

This pretty much gives your team good coverage.