Nice team, though I see a few things here and there...
Haxorus
As a pokemon: I think you like this guy, and I gotta admit, after 1-2 dragon dances, almost nothing stops it.
Item: Well considering how deadly of a sweeper this thing is after some dragon dances, Confusion isn't your only problem. If you get burned or paralysed, your haxourus could easily become useless. Thus Lum berry is superior as it can take out all three threats at once.
EVs and nature: Yup, glad to see you know your evs properly.
Moveset: I wouldn't say shadow claw is the best move for him
-Outrage-perfectly fine
-Earthquake-this is always seen on a pokemon that can learn it is it not :P
-Dragon Dance- duh
-Low kick/brick break- Shadow claw doesn't do the same as these two moves. Ferrothorn and air balloon heatran, and skarmory, are some of the most dangerous threats for haxorus. Ferrothorn won't take much from and earthquake, heatran can take you down when you try to pop that baloon, and skarmory just plain resists everything. these moves should solve this problem.
As a result
Haxorus@Lum Berry
Ability: Mold Beaker
EVs: 252 atk 252 spe 4 HP
Adamant Nature
-Outrage
-Earthquake
-Dragon dance
-Brick break/ Low sweep
This will be you new Haxorus
Espeon
As a pokemon:- I see you are trying to use espeon as a sweeper. I'm sorry to dissapoint but espeon's lack of bulk will leave you dissapointed when trying to set up. Therefore you should try using it as a lead.
Item: Replace with Light Clay, you will see why.
EVs and Nature: 252 HP 252 spe 4 def, you'll see why. Timid nature for speed.
Moveset: I'm gonna have to change this so excuse me. I'm gonna give you a dual screen set.
-Light screen
-Reflect- These two moves can allow a sweeper from your team to set up thanks to the defense boost. Light Clay will make sure that these last for eight turns, plenty enough time, and the EVs should let it put its max effort in setting up.
-Psychic/Psyshock-you'll probably want something to doafter setting up.
-Baton pass- Strange even though there isn't a stat boost to pass. This allows you to get past pursuit users, namely tyranitar and scizor. Pursuit can't do crap to espeon thanks to baton pass, and you get a safe switch in
-HP fire- Are you tired of scizor messing up your day, well not anymore. But tyranitar will still be a problem so watch out.
If you really want a special sweeper, then say hello to the biggest mustache in pokemon
Alakazam@life orb
Ability: Magic guard
EVs: 252 spa 252 spe 4 HP
Modest Nature
-Psyshock- You do not want Blissey to be a problem for you
-Focus blast- go to hell tyranitar
-Shadow ball- Latios and Latias will be taken care of with this move
-HP ice/fire- Dragons or steels, if focus blast cant do it, your pick
This is the premier psychic sweeper of OU, use him wisely, and if you want you can replace life orb with focus sash, either work. Its ability ensures that it works.
Hippowdon
As a pokemon: He's goin all right
Say hello to...
Landorus-T@ Choice Scarf
Ability: Intimidate
EVs: 252 atk 224 spe 32 HP
Jolly Nature
-Earthquake
-U-turn
-Stone edge
-Superpower
U-turn works amazingly with intimidate and choice scarf, allowing it to scout for dangerous moves and annoy physical attackers with intimidate. The choice scarf allows it to act somewhat as a revenge killer as well, which you need. Earthquake is STAB but be careful with the immunities. Stone edge provides great coverage especially with earthquake. Superpower is to hit stuff hard if you don't feel like using earthquake. This guy works great so use him.
Toxicroak
As a pokemon: He does exceptionally well in rain, but without, gets out classed by many...
I see that you are going for a bulky toxicroak. Guess who
Conkeldurr@leftovers
Ability: Guts
Evs: 120 HP 252 atk 136 spd
Adamant nature
-Bulk up
-Drain punch
-Mach punch
-Pay back
God, just look at that attack. Burning won't save you but it will only bring forth your demise witha 50% boost. Drain punch allows it to take a hit, and return the favor while recovering the HP lost. Mach punch allows it to overcome speed and finish off opponents. Pay back deals with ghosts types and possibly psychic if he survive a hit. I can see this thing being a beast on this team. So use it.
Gyarados
As a pokemon: Yes, he is usable on this team
Item: Wacan berry isn't the best choice as you will still have a tough time setting up. since your ability is moxie, the water gem is a superior item. Why you ask? With STAB and the 50% boost from the gem, waterfall reaches from 80-180 power, easily OHKOing anything that doesn't resist it, allowing you to get that first moxie boost that will destroy everything.
EVs and Nature: You got this down
Moveset: This is a nice standard moveset and I don't see much to fix. Good Job!
Jellicent
As a pokemon: I'm sorry, but having two water types in the same team can somewhat be disruptive and have bad synergy. You might have to replace it. But do not worry, this new alternative can act as good as jellicent while giving you the typing that your team needs. Presenting...
Heatran@leftovers
Ability: Flash fire
EVs: 248 HP 252 spd 8 def
Bold Nature
-Lava Plume
-Roar/Stealth rock
-Protect
-Will-O-Wisp
This is by far, my favorite heatran set. It's unique typing means it can't be stalled and it has the most resistances, second to magnezone(I think). Lava Plume is to attack and get in a burn, if you wanna burn head on, use will-o-wisp. If espeon manages to bounce some rocks, then you can troll with roar, or if you are gonna use alakazam then put in rocks for the sweepers to have an easier time, breaking sashes and providing the extra damage that can make a KO. Protect once burned, will stall hurt the opponent for one turn and then heal you in the same turn. Special defensive Heatran is definetely the poke for you and I guarantee you'll like it.
Nice team happy winning :D