Emerald Team Check

I'm building a team for pokemon Emerald. Note that the only battling I plan on using it for is against the Battle Frontier and some friends, no official competitive battling, so I haven't tried building the team around Smogon stuff or anything. Also, my team members are my six favorite pokemon, I won't change my team; some of them might be horrible team members but I'm doing my best to make it work. Also, I've bred all of these on my own (Besides Latios obviously), so their IVs are decent at the very least, most are pretty good.

I've never built a team like this before so I could really just use some advice. Here they are:

Aggron @ Choice Band
Ability: Rock Head
EVs: 252 HP / 252 SpD / 4 Atk
Careful Nature
- Earthquake
- Rock Slide
- Double-Edge
- Brick Break

Should I use Choice Band or Leftovers? Should I replace Brick Break with anything?
I think the main problem with this Aggron is his Attack is too low. I was trying to compensate for his low HP and Spd. What should I replace for Atk EVs?

Latios @ Twisted Spoon
EVs: 252 SpA / 252 Spe/4 HP
Timid Nature
- Dragon Claw
- Psychic
- Thunderbolt
- Ice Beam

Should I replace his item?

Absol @ Black Glasses
EVs: 4 HP / 252 SpA / 252 Spe
Modest Nature
- Bite
- Thunderbolt
- Flamethrower
- Ice Beam

I want to give him a physical attack because of his great attack, but the only good one is Shadow Ball, which is essentially a weaker version of Bite, with the same super effectiveness. Also, should I replace his item?

Cloyster @ Leftovers
EVs: 252 HP / 88 SpA / 148 SpD / 20 Spe
Calm Nature
- Spikes
- Surf
- Ice Beam
- Explosion

Any EV or item suggestions?

Nidoking @ Soft Sand
EVs: 152 SpA / 100 Atk / 252 Spe
Modest Nature
- Earthquake
- Megahorn
- Sludge Bomb
- Thunderbolt

Should he use Choice Band or Leftovers? And Ice Beam or Thunderbolt? I picked thunderbolt for help against water types. Also, how should I handle his EVs? Since he's mostly a physical attacker, it should be mostly attack.

Exploud @ Leftovers
EVs: 252 Def / 252 SpD / 4 Spe
Modest Nature
- Hyper Voice
- Shadow Ball
- Flamethrower
- Ice Beam

This Exploud is a mess. No idea why I went with defensive EVs. I wanted him to be a Special attacker before I realized how gen 3 does special/physical attacks based on type, so now he needs to be mixed. Really, I need help with his item, moves, and EVs.

Thanks a bunch guys.

Also fyi, all of these pokemon are level 99, with Latios being 100. At this point I won't be turning back to breed for different natures, which I wish I could in some cases, so please bear with me. I can still change their EVs though.

I've decided, Exploud is just really bad, and I've wanted Regice on my team for a while. How is this as a special wall?

Regice @ Leftovers
EVs: 252 HP / 112 Def / 144 SpA
Calm Nature
- Ice Beam
- Thunderbolt
- Rest
- SleepTalk