First of all, your team has no reliable walling except Cresselia, and stuff will set up on it if it uses Rest. Lunar Dance isn't a good move on your team since your removing your only means of defence, for something else.
From what I see, hard-hitters like Tyranitar can wipe out 4/6ths of your team, and even worse is the set-up sweepers, SDLucario, Sub/SD Garchomp, BulkyGyarados will have a field day with this team after Cresselia is sufficiently weakened.
Mainly lack of walling sans Cresselia leaves this team open to assault by fast and powerful sweepers such as Gengar, and to a lesser extent Deoxys-E.
No pokemon to take sleep is also hindering this team, if a pokemon uses a sleep move like Hypnosis, one of your members is incapacitated for the rest of the battle (unless you get lucky).
No Psuedohazer (pokemon with Roar, Whirlwind, etc.) or Hazer (pokemon with Haze) means you cannot effectively deal with Baton Pass, especially Ninjask leads.
For starters, I would keep Swampert, Cresselia, Dragonite. I would center this team somewhat around Dragonite, since it is quite powerful. Basically the team would work around eliminating/incapacitating the stuff that would KO Dragonite, and let Dragonite pull off a sweep.
Swampert should be given this set to start with, and to counter some physical threats.
Swampert @ Leftovers
Relaxed, 240 HP, 216 Def, 52 SpA
Earthquake
Ice Beam
Hydro Pump / Surf
Stealth Rock
If you want to use Cresselia for walling, you essentially have two choices:
- Use Moonlight for recovery, but will be ruined by Sandstorm
- Use Rest/Sleep Talk, giving your team a status absorber BUT takes up one extra moveslot that could be used for something else
Personally I'd go Rest/Stalk.
Cresselia @ Leftovers
Calm, 252 HP, 252 SpD, 4 Satk (If you have Calm, switch the Def and SpD EVs)
Rest
Sleep Talk
Ice Beam
Thunder Wave/Charge Beam/Psychic
Thunder Wave should be used as Dragonite is rather slow, allowing Dragonite to outspeed some stuff and KO. You would be using this Cresselia for Special walling.
I would recommend Hippowdon for a physical wall. Both can Psuedohaze and Hippowdon can set up Sandstorm, disabling Moonlight Cresselia, one of the main counters to Dragonite, and it does a nice job countering physical stuff.
Hippowdon @ Leftovers
Impish, 252HP 252Def 4Atk
Earthquake
Ice Fang
Slack Off
Roar
For Togekiss, what you were looking for was mainly a bulky Wishpasser. I feel Jirachi does the job better, bulkier and more resistances, and providing paralysis support.
Jirachi @ Leftovers
Wish
Body Slam
Zen Headbutt
U-turn/Reflect/Light Screen
Last slot would go to sweepers. Main priority would be to stop stuff with Ice Beam and provide offense.
I would go with a Tyranitar with Pursuit. Too lazy to list set here, but CB is the most effective.
For Dragonite Outrage > Dragon Claw, and Dragon Dance > Thunderpunch, as you're going to be kamikaze OHKOing everything with Outrage at lategame with a Dragon Dance.
This is only a draft, not a perfect team by any stretch, so you have to mix and match to find which combos work for you. By the way, your sets aren't very good, but I'll leave it to someone else to do the nitpicking.
I hope you spend the time to read through this wall of words (557 words)