Help me complete my team.

[Yoshi625]

I am looking for a final pokemon for my team, my current team consists of:

Mega Salamence @ Salamencite
-Jolly
-252 Atk, 252 Speed, 4 Def
-Earthquake
-Return
-Dragon Dance
-Outrage

Sylveon @ Choice Specs
Ability: Pixilate
EVs: 56 HP / 200 Def / 252 SpA
Quiet Nature
- Hyper Voice
- Moonblast
- Shadow Ball
- Psyshock

Staraptor @ Choice Band
Ability: Reckless
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Brave Bird
- Double-Edge
- Close Combat
- U-turn

Cresselia @ Leftovers
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Icy Wind
- Psychic
- Helping Hand
- Swagger

Landorus-Therian @ Leftovers
Ability: Intimidate
EVs: 184 HP / 236 Atk / 88 Spe
Adamant Nature
- Earthquake
- Rock Slide
- U-Turn
- Protect

*EMPTY SLOT*

What would be a good 6th Pokémon to finish my team?