Well, I just battled this team, and Umbreon destroyed it :P so I see you've added in a fighting type to fix that, which isn't bad. Machamp isn't the best around though, and I have some general improvements to make to the team. Let's go :]
Ambipom
Okay, gonna be honest here, Ambipom isn't that great. It just doesn't have enough power to keep up with most of the tier, and is wayy too frail and predictable. So, to nail two birds with one stone, let's replace him with Mienshao. He fulfills the same scouting role as Ambipom, but he packs a huge punch while also scaring out Dark types. The icing on the cake is the amazing ability Regenerator, which in conjunction with U-turn nets free damage on the opponent every time he's in.
Mienshao (M) @ Life Orb
Trait: Regenerator
EVs: 252 Atk / 252 Spd / 4 HP
Jolly Nature (+Spd, -SAtk)
- Fake Out
- Hi Jump Kick
- Stone Edge
- U-turn
Zapdos
Looks good. One thing I would change is Roost over AncientPower - it doesn't really get you any extra coverage and the chance to raise all of your stats is too uncommon to rely on. A Life Orb would also be a nice item choice now you have reliable recovery in Roost. You should consider HP Grass over Ice as your team has more of a problem with bulky Waters like Swampert than Flygon. Also, Lightningrod is sadly unreleased, so Pressure is your only option.
Umbreon
Mean Look doesn't really have a huge purpose here, and one of Umbreon's main selling points is its ability to Wish pass. I'd go with Wish/Protect/Foul Play/Toxic.
Suicune
Suicune as a SubCMer is pretty much outclassed by Raikou, who sports higher Special Attack and Speed. One thing Suicune does have over Raikou though, is its amazing bulk. It is famous for its very effective RestTalk set. Go with this:
Suicune @ Leftovers
Trait: Pressure
EVs: 252 HP / 252 Def / 4 SDef
Bold Nature (+Def, -Atk)
- Scald
- Calm Mind/Roar
- Rest
- Sleep Talk
Machamp
Machamp... again, not a great 'mon, and pretty redundant with the addition of Mienshao to your team. As your team is lacking Stealth Rocks and a Steel type, I suggest a Bronzong in this spot. He can tank lots of hits and set up rocks, helpful for wearing down switchins and breaking sashes.
Bronzong @ Leftovers
Trait: Levitate
EVs: 252 HP / 252 Def / 4 SDef
Relaxed Nature (+Def, -Spd)
- Stealth Rock
- Gyro Ball
- Earthquake
- Toxic
Flygon
Well, Flygon is a great poke in the right hands, but you're not using it to its full potential. It runs an awesome Choice set because of it's great resistances and immunities, access to U-turn, and virtual immunity to entry hazards. Scarf would probably be preferred as this team is lacking a revenge killer, but Band is cool too for extra power.
Flygon (F) @ Choice Scarf/Choice Band
Trait: Levitate
EVs: 252 Atk / 252 Spd / 4 SDef
Jolly Nature (+Spd, -SAtk)
- Earthquake
- Outrage
- Fire Punch/Stone Edge/Dragon Claw
- U-turn
