RU team

This is a team I made for use in Pokemon Showdown's RU. Now I've never played competitive before so I just kind of threw this together with Pokemon I liked and what I knew of their various roles. I've been doing pretty well with this team having about a 3:2 win:lose ratio.

Any CC is greatly appreciated.

Modest Mesprit @ Expert Belt*
Levitate
EVs: 56/0/100/252/100/0
- Psychic
- Stealth Rock
- Ice Beam
- Calm Mind*
Notes: Mesprit leads and either sets up SR or Psychic/Ice Beam's depending on the opponent's lead. I'm not too sure about the item so I put an Expert Belt just to add on to any super effective damage he might do, particularly against dragons and bulky grass types.

Lonely Archeops @ none
Defeatist
EVs: 4/252/0/0/0/252
- Acrobatics
- Rock Slide
- Earthquake
- U Turn
Notes: Archeops comes in and uses Acrobatics as his default and changes attack depending on the opponent. If he gets below the 50% and Defeatist activates, I either leave him in or U Turn to keep him as death fodder for later on.

Modest Amoongus @ Black Sludge
Regenerator
EVs: 156/0/0/100/252/0
- Clear Smog
- Giga Drain
- Spore
- HP Fighting*
Notes: Amoongus' job is to tank special attacks since between he and Uxie, he has the higher base Sp Def and Uxie has the bonus of resisting fighting type attacks. Spore + Giga Drain and Regenerator for HP recovery, HP fighting for ice types and Clear Smog to deal with anything that tries to set up on him. Although I'm thinking to switch HP Fighting for Toxic.

Timid Galvantula @ Choice Specs
Compoundeyes
EVs: 0/0/0/252/4/252
- Volt Switch
- Energy Ball
- Bug Buzz
- HP Ice
Notes: Galvantula is a typical special attacker normally using Volt Switch to deal STAB damage and get around the Choice Specs. But there have been times when he was my last guy and the Choice Specs worked against him.

Naughty Cinccino @ Shell Bell*
Skill Link
EVs: 4/252/0/0/0/252
- Rock Blast
- Bullet Seed
- Tail Slap
- Return
Notes: I used one of these in my White Playthrough with the exact same moveset. Only the ability was Technician to boost the power of all the moves except return. Here I used Skill Link coupled with a +ve Attack nature and Attack EVs to get the most out of her chain attacks. Return is just for STAB damage. I also have no idea what item to give her so she's been using the Shell Bell thinking she would get HP back for each hit of her chains.

Careful Uxie @ Light Clay*
Levitate
EVs: 252/56/100/0/100/0
- Reflect
- Light Screen
- Zen Headbutt
- Thunder Wave*
Notes: Uxie sets up screens, T-Waves and then Zen Headbutts for flinching. I would like to get some form of HP recovery on him but that would have to be Leftovers which takes away the Light Clay or Rest which I'm not that comfortable with not having the Chesto Berry. Any ideas?

Mesprit should choose between one of Calm Mind or Stealth Rock. I'd recommend making Uxie the Stealth Rock setter (more on that later), and make Mesprit have Calm Mind:
-Calm Mind
-Psychic/Psyshock
-Ice Beam
-Thunderbolt
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb

or
-Substitute
-Calm Mind
-Psyshock
-Ice Beam/Thunderbolt
Nature: Timid
EVs: 96 HP/248 SAtk/164 Spe
Item: Leftovers

Archeops is better off as Hasty, because it needs all the Speed it can get, and it's outsped by +Speed Galvantula otherwise. I'd have Earth Power over Earthquake if I were you, since it lets Archeops hit physical walls like Steelix harder than Earthquake would. Give Archeops the Flying Gem; it combos really well with Acrobatics. If you use Acrobatics, not only will it gain the doubled power (without the item), the consumed gem will increase its power (for one attack only).
Calcs:
With Flying Gem: 55 x 1.5 (STAB) x 1.5 (Flying Gem) x 2 (Flying Gem is consumed, making Archeops item-free to make Acrobatics double its power) = 247.5 ~ 247

From that point onward, Acrobatics will have 165 base power, factoring in STAB and no item.

Amoonguss should utilize a defensive spread to match its role on the team; use a Calm nature with 252 HP/88 Def/52 SAtk/116 SDef. HP Fire is preferred over HP Fighting for the harder hit on Escavalier and Ferroseed.

Galvantula is best known for its 91% accurate Thunders courtesy of CompoundEyes, so you should take advantage of that fact:
-Thunder
-Bug Buzz
-Hidden Power (Ground)
-Volt Switch/Giga Drain
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Choice Specs
Ability: CompoundEyes

Rapid Spin support is really, really crucial on this team because Archeops and Galvantula are weak to Stealth Rock, and Archeops is rendered useless if its HP dips below half. Consider Kabutops for Rapid Spin support, as well as Alomomola for Wish support over Cinccino:
Kabutops:
-Stone Edge
-Aqua Jet
-Rapid Spin
-Swords Dance/Waterfall
Nature: Adamant
EVs: 4 HP/252 Atk/252 Spe
Item: Life Orb/Lum Berry
Ability: Weak Armor

Alomomola:
-Waterfall
-Wish
-Protect
-Toxic
Nature: Impish
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers
Ability: Regenerator

If you want to keep Cinccino, (it's useful if you can't fit in a Rapid Spinner to deal with hazard leads like Smeargle or Crustle, since it can use its multi hit moves to KO those Pokemon through their Focus Sash or Sturdy) change the nature to Jolly. No matter how tempting it is to boost its power with a +Attack nature, Cinccino will then find itself outsped by base 105 Speed Pokemon and higher, like offensive Cryogonal and opposing Galvantula. Really, I don't see a reason why Cinccino should have Return, since a STAB 5-hit Skill Link outdamages it. Replace Return with Aqua Tail to hit weakened Aggron and Steelix. The only time you should use Adamant is if Cinccino is using Choice Scarf to make up for the lost power. Tl;dr:
-Tail Slap
-Bullet Seed
-Rock Blast
-Aqua Tail
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Life Orb
Ability: Skill Link

or
-Tail Slap
-Bullet Seed
-Rock Blast
-U-turn
Nature: Jolly/Adamant
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Band (Jolly)/Choice Scarf (Adamant)

Now, on to Uxie. Since I made Mesprit the Calm Mind attacker, I've given it the role of Stealth Rock user along with its Dual Screening role. It's not meant to be an attacker, but a supporter:
-Reflect
-Light Screen
-U-turn/Memento
-Stealth Rock/Thunder Wave
Nature: Jolly
EVs: 252 HP/4 Def/252 Spe
Item: Light Clay

Honestly, where do you get your EV spreads from?

I made some of the changes you suggested like Archeops and Cinccino. I'll have to test out the team later on today.

I agree with you on the Rapid Spin. I noticed SR damage can add up on everyone but I don't really want to get rid of anyone. If I do though it'll be Galvantula.

May I suggest something? I think it's a good idea to have a Steel-type on your team because none of your Pokemon at the moment resist Ice, Dark or Rock. Klinklang is a good choice because it can switch in on Uxie/Mesprit and Archeops' weaknesses. It can act as a setup sweeper as well which none of your Pokemon have. Because you have two Psychics and one of them has the important Stealth Rock, I'd drop Mesprit in this case.

Here's a set which utilizes Shift Gear, Klinklang's signature move.

~ Shift Gear
~ Gear Grind
~ Wild Charge
~ Substitute
Item: Leftovers/Life Orb
Ability: Clear Body
Nature: Adamant