Super Uber Team

Heatran : Modest : Life Orb : Flash Fire
Magma Storm, Metal Sound, Earth Power, Stealth Rock
EVs: 255 Sp.Atk / 255 Defence
Celebi : Modest : Sitrus Berry : Natural Cure
Leaf Storm, Phychic, Perish Song, Magic Coat
EVs: 255 Sp.Atk / 200 Sp.Def / 55 Defence
Latios : Timid : Soul Dew : Levitate
Luster Purge, Draco Meteor, Phyco Shift, Ice Beam
EVs: 255 Sp.Atk / 255 Speed
Rhyperior : Adament : Focus Band : Solid Rock
Earthquake, Rock Wrecker, Hammer Arm, Thunder Fang
EVs: 255 Attack / 255 Sp.Def
Zapdos : Modest : Damp Rock : Pressure
Thunder, Rain Dance, Roost, Light Screen
EVs: 200 Speed / 200 Sp.Atk / 55 Sp.Def / 55 Hp
Darkrai : Mild : Bright Powder : Bad Dreams
Dark Void, Dream Eater, Double Team, Nightmare
EVs: 255 Hp / 255 Defence


I love this team.... My freinds never win in an Uber battle against me XD

Um first thing first, evasion moves are banned this includes double team, minimize and others, so straight away you need to change your Darkrai set. I would suggest a nasty plot set.
Darkrai
Item: Life Orb
Nature: Timid
Ability: Bad Dreams
EV's: 252Speed/252SpAtk/4Hp
Move 1: Dark Void
Move 2: Nasty Plot
Move 3: Dark Pulse
Move 4: Focus Blast

Next your team is pretty weak to Kyogre. Nothing will switch into a Water spout, even celebi is 2hit Koed by a modest scarfed varient. To fix this problem this is what I would do. First I would change celebi for Ferrothorn. Dont let Ferro's status of an Ou pokemon fool you, he is a fantastic pokemon in Ubers. This is what set you should be running.
Ferrothorn
Item: Leftovers
Nature: Sassy
Ability: Steel Thorns
EV's: 252HP/252SpDef/4Def
Move 1: Stealth Rock/Spikes
Move 2: Leech seed
Move 3: Protect/Power Whip
Move 4: Thunderwave/Gyro Ball

Next Id replace rypherior with Palkia, he can switch into a water spout and threaten with powerful attack such as spacial rend and thunder.
Palkia
Item: Choice Scarf
Nature: Hasty/Timid
Ability: Pressure
EV's: 4Atk/252SpAtk/252Speed
Move 1: Spacial Rend/Draco Meteor
Move 2: Surf
Move 3: Thunder
Move 4: Fire Blast/Outrage/Draco Meteor

Okay some other things I would do are; replace Zapdos, hes not that good in Ubers. I would suggest Kyogre (Most used Uber for a reason), Mewtwo, Groundon, Giratina, Soul Duel Latias, Garchomp and Arceus are all good trades. You could also possibly replace Heatran with one of the pokemon mentioned above but make sure you raplace Zapdos first. Also some of your pokemons sets need a bit of work, since your running sould duel on Latios Draco Meteor seems a wast. Replace it with a calm mind set; calm mind, dragon pulse, surf/gras knot/thunder, recover/HP Fire with a timid nature and max evs in speed and spec attack. If you dont replace heatran swap his set to a stall breker set, it works very well in Ubers.

First things first: Heatran is seriously outclassed in Ubers. Reshiram easily replaces it:
-Blue Flare
-Draco Meteor
-Dragon Pulse
-Flamethrower/Stone Edge/Outrage
Nature: Timid/Hasty
EVs: 4 HP or Atk/252 SAtk/252 Spe
Item: Choice Specs/Choice Scarf

Definitely replace Zapdos with something else; it's not that good there. Since you have Reshiram, how about Groudon, for sun support?:
-Stealth Rock
-Earthquake
-Stone Edge/Fire Blast/Lava Plume
-Dragon Tail/Thunder Wave/Toxic
Nature: Impish
EVs: 252 HP/4 Atk/252 Def
Item: Leftovers

If you choose to use Groudon, you'll have to give up Ferrothorn, because its weakness to Fire is amplified in Sun, and in their place, use Blaziken to take advantage of the sun Groudon provides (I'm not suggesting Ho-oh because it's dependent on Rapid Spin support):
-Swords Dance
-Flare Blitz
-Hi Jump Kick
-Protect
Nature: Adamant/Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Leftovers/Life Orb
Ability: Speed Boost

Non-Soul Dew Latios doesn't fare well in Ubers. Going with what Potent said, use Garchomp or Mewtwo instead:

Garchomp:
-Swords Dance
-Outrage
-Earthquake
-Stone Edge/Fire Fang
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Life Orb/Lum Berry

Mewtwo:
-Calm Mind
-Psystrike
-Ice Beam
-Fire Blast/Aura Sphere
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb

Um Heatran is most certainly not outclassed in ubers at all. Its one of the best stall breakers and support mons in general in the tier thanks to its awesome resistances and additionally not SR weak. =/

Also @ OP, there is a difference between Ubers and legendaries. Certain legendaries are not good in ubers, Zapdos and Celebi are some of those mons, Heatran is an exception though. Celebi is outclassed by Grass Arceus who also beats Kyogre and Zapdos is outclassed by Zekrom and Electric Arceus offensively and Lugia, Giratina and whatnot defensively since they essentially also beat the same things much better.

Rhyperior is also outclassed by Groudon and even Tyranitar in ubers.

Also Soul Dew hasnt been released unless this is a gen 4 or DW team.