RU/Competition Team Rate/Help?

Hey so I just got into Competitive battling :) ! I could really use some advice, plus I don't really know anything about EVs or IVs so I won't be posting those... but here's my team! (all level 100 except Smeargle)

Lead
Smeargle @Focus Sash
Ability: Own Tempo
-Trick Room
-Spore
-Endeavor
-Dragon rage

Basically a suicide Pokemon to set up Trick Room and kill the first Pokemon on an opponents team.

Slowking @Leftovers
Ability: Oblivious
-Fire Blast
-Surf
-Psychic
-Trick Room

Cofagrigus @Leftovers
Ability: Mummy
-Trick Room
-Nasty Plot
-Shadow Ball
-Calm Mind

Aggron @Choice Band
Ability: Rock Head
-Head Smash
-Earthquake
-Aqua Tail
-Ice Punch

Druddigon @Choice Band
Ability: Rough Skin
-Outrage
-Sucker Punch
-Superpower
-Dragon Claw

Mesprit @Life Orb
Ability: Levitate
-Trick Room
-Psychic
-Thunderbolt
-Healing Wish

I worked really hard to get this team (including breeding to get egg moves!) so don't go to hard on me. I also have a silly question: When Competitive battling, can two pokemon hold the same item? I've heard yes and no, so I just want a final answer. This is my Black 2 team.

Thanks!

Guide to EVs. They're very important in competitive play, as are natures, so you must always take them into account when making teams.

Always use Regenerator as Slowking's ability. Oblvious and Own Tempo are useless.

Slowking should be Quiet with 248 HP/252 SAtk/8 SDef.

Cofagrigus is UU and isn't allowed on RU teams. Find something else to use.

Aggron and Druddigon should be Brave with 252 HP/252 Atk/4 Def.

Mesprit should be Quiet with 252 HP/252 SAtk/4 SDef.

Some battles have "Item clause," which prevents the use of 2 of the same item on the team. Random Matchup and Battle Subway uses this feature. Simulator battles (or maybe link/Wi-Fi battles) don't use this clause.

As you've picked the banned Cofagrigus, I'd replace it with something to hit steel-types supereffectively. Fighting types are great choices, as their STAB moves also hit the Normal and Dark types supereffectively, troubling common walls such as Lickilicky. Pokemon with high attack, such as Hariyama, Hitmonlee, Emboar or Medicham should fit nicely to your team.

Also, I would suggest dragon tail for aggron:)