Rate my vgc 2016 team

Question

Hi I made this team for vgc2016.
I have big problems with mega-gengar and mega-salamence.
Please rate my team

Groudon-Primal @ Red Orb
Ability: Desolate Land
EVs: 60 HP / 160 Atk / 36 SpD / 252 Spe
Jolly Nature
- Substitute
- Precipice Blades
- Fire Punch
- Protect
This is one of the legendary of the team, It 2ohko a lot of things (a-kyogre, xerneas, m-kangashkan and other). Precipice Blades it's one of the Stab moves, fire punch it's the other, protect it's for earn a free turn and substitute it's for wait when another Pokemon kill a-kyogre.

Kangaskhan @ Kangaskhanite
Ability: Scrappy
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature
- Double-Edge
- Protect
- Ice Punch
- Fake Out
It's the mega of the team, it's the best Pokemon of the team. Double-Edge is the Stab moves for make a lot of damage.
Protect is for earn free turn.
Ice Punch is for hit dragons and flying type like m-salamence thundurus landorus...
Fake out is for flinch

Thundurus @ Leftovers
Ability: Prankster
EVs: 216 HP / 130 Def / 56 SpA / 96 SpD / 12 Spe
Timid Nature
- Taunt
- Thunder Wave
- Discharge
- Hidden Power [Ice]
I use it very rarely, it's a supporter with a Classic set.
Taunt for the opposite supporter
Thunder wave for the speed control
Discharge for make damage at water type like a-kyogre or Flying type like talonflame
Hp ice for coverage

Xerneas @ Power Herb
Ability: Fairy Aura
Level: 50
EVs: 4 HP / 116 Def / 200 SpA / 188 Spe
Modest Nature
IVs: 1 Atk / 30 SpA / 30 SpD
- Dazzling Gleam
- Hidden Power [Ground]
- Geomancy
- Protect
It's the Classic Geomancy set except I prefer hp ground for hit a-groudon.
Dazzling Gleam is for hit two Pokemon with a stab move.

Crobat @ Sitrus Berry
Ability: Inner Focus
Level: 50
EVs: 164 HP / 4 Atk / 20 Def / 76 SpD / 244 Spe
Jolly Nature
- Brave Bird
- Super Fang
- Taunt
- Tailwind
Crobat is a supporter
Brave bird is a stab offensive move.
Super Fang is for make a half life damage.
Taunt is for the opposite supporter
Tailwind is for speed control.

Cresselia @ Wiki Berry
Ability: Levitate
Level: 50
EVs: 252 HP / 136 Def / 4 SpA / 116 SpD
Calm Nature
IVs: 0 Spe
- Skill Swap
- Helping Hand
- Trick Room
- Ice Beam
Cresselia is for counteract the opposite trick room user.
Skill swap for change ability.
Helping hand for support the sweeper
Ice beam is the offensive move.

Comments

Kangaskhan: Double-Edge racks up recoil damage very quickly. Without any healing on your team it is not going to last long. Return has almost as much power with no recoil.

Cresselia: Skill Swap isn't a very useful move on Cresselia because it is usually very situational. Possible alternatives include Morning Sun/Rest (reliable recovery), Toxic/Thunder Wave (status), and Lunar Dance (team heal).

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Sitrus berries and wiki berries are usually only good on Pokemon with unburden or belly drum. Replace them with leftovers.

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Kangaskhan doesn't like constant Double-Edge recoil, use Return instead. You could also replace Protect with Power-Up Punch for more Attack

Xerneas: Replace Protect for an offensive move such as Thunder, Focus Blast or Psyshock.

Crobat: Use Black Sludge instead of Sitrus Berry. Roost is a viable and recommended option to keep Crobat fighting longer.

Cresselia: Useful, but get rid of Trick Room. All of your Pokemon are relatively fast except P-Groudon, and you have max Speed. Skill Swap is actually useful in stopping Pokemon like M-Kangaskhan, M-Salamence and even Landorus-T from sweeping your whole team. Helping Hand is a nice choice, but Toxic or Morning Sun are viable, especially Morning Sun with Groudon. However, Cresselia needs Trick Room to be of use. So either run a slower team, or change it out for another Pokemon (maybe Life Orb Alakazam?)

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Thank you for the answer
@Awildnoobappared I'll try morning sun instead skill swap
@Mega Luxray I'll try all. Trick room on cresselia it's not a move I use for my team but I use it when the opposite team use trick room for reset the speed control