Rate My Mixed Team

Okay, anything in BOLD is Kudos to Aeropostle from pc forums

Cresselia @ Leftovers
Bold Nature
Trait: Levitate
252 HP / 108 Def / 148 SpD
Ice Beam
ThunderWave
Reflect
Charge Beam

Salamence @ Life Orb
Rash Nature
Trait: Intimidate
120 Atk / 252 SpA / 136 Spe
Brick Break
Draco Meteor
Fire Blast
Roost

Breloom @ Toxic Orb
Adamant Nature
Trait: Poison Heal
48 HP / 252 Atk / 208 Spe
Swords Dance
Mach Punch
Seed Bomb
Spore

Hippowdon @ Leftovers
Impish Nature
Trait: Sand Veil
252 HP / 16 Atk / 152 Def / 88 SpD
Earthquake
Slack Off
Ice Fang
Roar

Blissey @ Leftovers
Modest Nature
4 HP / 252 Def / 252 SpA
Calm Mind
Ice Beam
Thunderbolt
Softboiled

Dusknoir @ Leftovers
Impish Nature
252 HP / 252 Def / 6 SpD
Fire Punch
ThunderPunch
Pain Split
Trick Room

cresselia looks like its supporting with twave and reflect, but it needs a recovery move to survive, moonlight is the only thing it has but sandstorm will only lets it get 25% recovery as well remove the leftovers gain. i would have psychic as a stab move instead of ice beam because dragons arent very common anymore, but its still useful so its up to you.

salamence dies faster in a sandstorm.

breloom with swords dance is hard to pull of since its sort of fragile and slow, but if you get it to work, you can sweep easily.

hippowdons ability is sandstream.

calm mind blissey is nice but the hp loss makes it easier to be physically killed. you could try serence grace and charge beam but calm mind is better with its spdef plus.

trick room probably wont help cress breloom or salamence so use it carefully.

Looks to me like your team is a stally kind of type that weakens the opponent then sweeps with Breloom, while revenge killing with salamence, so i'll take that approach to this team.

With any stall team, it's highly preferable to have a spikes user, which only forretress, froslass, skarmory or roserade can use effectively, due to resistances or immunities they have. I suggest Skarmory since that has whirlwind, to rack up more damage, also, hippowdon covers the electric weakness while blissey can handle special fire hits and salamence can somewhat handle physical fire attacks. If you feel like you need rapid spin, which you shouldnt, since only one pokemon is weak to it, use forretress.

Now with cress. Cress is a bad lead in general, also the set seems odd for a stallish team. I would go for Toxic, Rest, Sleep Talk and maybe Psychic, however you are walled by steels, but you can take care of them with salamence. Also, make hippowdon your lead and give it stealth rock over ice fang or roar.

Thirdly, on dusknoir, you really dont need trick room with a stall team, so i would switch that to either Will-O-Wisp, since you are rather Gyarados weak.

I feel like im changing too much, so you can keep using Calm Mind bliss, but make sure they don't have any powerful hard physical hitters left like heracross or machamp, or even tauros and the like.

On a last note, toxic spikes is nice but since Cress will have toxic and Dusknoir has will-o-wisp, it should be fine.

Hope it helps and good luck =D