This team will have trouble going up against bulky waters such as Milotic.
You definately need a wall and a sponge on your team.
Chimecho shouldn't really be focused on attacking at all. It's main role is support.
If you want Swampert to have Rest give it Sleep Talk at least. Sleeping for two turns will hurt you. Your opponent will not sit there and wait.
Metagross...hmm depends on what you want. Want a sturdy one go with Kazaams. Though I recommend Thunderpunch over Zen Headbutt if you can get it. Helps against your bulky water weakness.
Then there is Agiligross...
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Adamant
252 Atk/104 Spd/152HP
-Meteor Mash
-Earthquake
-Agility
-Explosion
With one Agility Metagross outspeeds its enemies. This ocmes in handy when it is time for an Explosion.
EDIT: Whoops didnt see the Trick Room comment. Ignore the Agiligross part. But it is still useful especially when all your TR users are KOED.