Competitive team needs help

Seviper Adamant @Life Orb
252atk/252spe/4hp
Earthquake
Giga Drain
Crunch
Poison Jab
Mainly there just to be there as it's one of my favorites. It's a decent sweeper, can't find anything better atm. Although Poison moves have terrible coverage I like poison jab because of the stab.

Blastoise Modest
252 Sp.atk/252spe/ 4 hp
Focus blast
Protect
Surf
Flash Cannon
My special sweeper, Kinda weak atm but It'll do. I could use it as a supporter, but I'd need to breed it. I could do that, and with HG SS coming out soon I might.

Lucario Jolly
252Atk/252spe/ 4hp
Crunch
Extremespeed
Stone Edge
Close Combat
My second favorite of the team, I've had it sweep teams before. It's actually my second fastest Pokemon, Electivire being the fastest, Stone edge hurts Skarm and other flying types who actually can put quite a dent my Lucario

Electivire Lonely @ Expert Belt
Need the Ev spread for this please I'm in the midst of eving it now
T-bolt
Earthquake
Ice punch
Cross Chop
Hitting 14 types for super effective hits is nothing to sneer at. so I added this as a must. Problem is, I don't know the EV spread

Donphan Impish @ Leftys
252def/ haven't maxed out the other ev's yet.
Ice shard
stealth Rock
Rapid spin
Earthquake
Rapid spinner and Stealth rocker, He's actually my lead, and more of a supporter, set's up Stealth rock then just sits there Ice Sharding and Eq'ing away.

Umbreon Relaxed @ leftys
252def/252spD/4hp
Toxic
Dark pulse
Moonlight
Mean Look
annoyer another one who can just stall till the sun is high. It just Mean looks first, then toxic, and moonlights when it's at half HP. great staller.

This team needs a bit of help, so I'd very much appreciate it if you could help me with it.

Seviper has no business leading a team or being on a competitive OU team. There are any number of options that could go better in that spot. It's best not to lead with an all-out sweeper since they are usually pretty useless in that position, so go with something to set up hazards and/or deal with other common leads. Bronzong randomly pops into mind to set up SR as well as giving your team a bulky steel type to deal with Dragon attacks, which pretty much massacre your team right now.

Dragon Dance Gyrados pretty much 6-0's you with proper support, so I'd consider adding bulky offensive Suicine > Blastoise to solve this:

Suicune @ Leftovers
Timid
172 HP / 120 SpA / 216 Spe
- Calm Mind
- Surf
- Ice Beam
- HP Electric

Add Swords Dance > Stone Edge on Lucario and give him an adamant nature, otherwise he's not nearly as effective. Close Combat OHKOs Skarmory after a SD and Life Orb boost with Stealth Rock damage. \o/

Electivire wants 36 Atk / 252 SpA / 220 Speed with a Mild nature.

52 HP / 252 Atk / 204 Def on Donphan.

Always max HP on Umbreon, and there's no point in a pure stalling Umbreon if you have no way to rack up residual damage, aka spikes/sandstorm. A wish set would be cool since your team lacks any form of healing otherwise =(

Still there are a lot of weaknesses here, read through this OU threats guide to make sure you have all the important stuff covered. There's not really a lot of synergy going on here, nothing is supporting each other or opening up any sweeps for teammates. Teams should have a central focus to build around so there's some sort of goal and you're not just throwing 6 random pokemon together.

ty for the input, I don't really have a lot of EV'd Pokemon, so I just threw what I had together, I'll certainly take a look at the guide, I should have put my team in order, Donphan is actually my lead.