Hi there! Nice team, I got a few suggestions for you.
You're really weak to hail and sun teams and if you're looking for a pokemon that can go out with a bang, may I suggest snorlax in place of metagross?
Nature: Brave(-Spe + Atk)
Ivs: 0 Spe
252 HP / 252 Atk / 4 Def
Trait: Thick Fat
-Crunch / Superpower
-Double Edge / Rock Slide
Just look at the grin? It's too adorable to resist! Snorlax is a better pokemon than metagross(or your team, specifically) because it can tank blizzards, heatwaves, and discharges which your team is quite weak to. Second, Snorlax' selfdestruct is more powerful than metagross' explosion! Snorlax also works well with your cresselia, being able to target ghost and dark types that cress has trouble with, while also being able to spam earthquakes w/o trouble. Rock Slide is also a fun move that hits both targets and can do some serious damage to hail and sun team. It's also pretty slow, which means nothing outspeeds it in trickroom.
One more suggestion, if you're looking for a spore user and a rain counter, you should try amoongus in place of breloom.
Nature: Sassy(- Spe, +SpD)
Ivs: 0 Spe
EV 248 HP / 8 Def / 252 SpD
-Protect / Sludge Bomb
This is pretty much the onsite set. Well first off, amoongus is a hell of a lot bulkier than breloom, which will do you good in being to deal with rain teams in general. Second thing that makes it good is spore, which shuts down counters. Amoongus also has regenerator which allows it to switch out and regain health, meaning it isn't worn down so easily. Rage powder is also a cool move, you can lead with amoongus and Trick room user, have amoongus use rage powder to take the taunts away from cress or dusclups and allowing you to get an almost guaranteed set up. Amoongus is better than breloom in that it can sponge hits better, aid your team in setting up trick room and functions decently in it to begin with.
Well that's all for now. Happy team building!