Party thoughts.

[Calyx]

I was reading the tutorial on breeding a party and part one is actually getting your party. So i thought I'd ask for some thoughts on my current party. for OR. I don't really know what pokemon are "good" competitively, so I'm really just using what I like. (My party was all leveled during game, or traded, so i don't know their EVs)

My current party is

Charizard
Ability: Blaze
EVs: unknown
Docile Nature
- Heat Wave
- Dragon Pulse
- Earthquake
- Solarbeam
Item: Charizardite Y

Garchomp
Ability: Sand Veil
EVs: unknown
Lonely Nature
-Iron Head
-Dragon Rush
-Earthquake
-Flamethrower


Lucario
Ability: Steadfast
EVs: unknown
Hasty Nature
-Power-up Punch
-Me First
-Aura Sphere
-Bone Rush

Eevee (I will evolve it into Umbreon tonight)

Starmie
Ability: Illuminate
EVs: unknown
Hardy Nature
-Surf
-Psychic
-Thunderbolt
-Dazzling Gleam

Gardevoir
Ability:Synchronize
EVs: unknown
Hardy Nature
-Magical Leaf
-Psychic
-Shadow Ball
-Moonblast

I'm considering subbing out Charizard and Umbreon for Blaziken and Snorlax respectively. Also I'm not really sure about movesets right now. Any advice as far as suitable substitutes, held items, abilities etc would be greatly appreciated!