Rate my first competitive team

[GhastlyClare]

Hi everyone! I finished the game and decided to try battling. I'm creating a team out of newly bred pokemon, but I'm a newbie to both battling and team building, so my team will probably have some weaknesses I can't notice, that's why I need your insight. So far, the pokemon I am going to use are:

Skarmory@Rock helmet
Ability: Sturdy
Nature: Adamant
EV: 252 Def/252 HP/4 Atk
-Roost
-Brave Bird
-Stealth Rock
-Whirlwind

Chansey@Eviolite
Ability: Natural Cure
Nature: Bold
EV: 252 Def/252 SpD/4 HP
-Soft-Boiled
-Heal Bell
-Toxic
-Earthquake

Lucario@Muscle Band
Ability: Justified
Nature: Jolly
EV: 252 Atk/252 Spe/4 Def
-Swords dance
-Close Combat
-Bullet Punch
-Ice Punch

Gengar@Gengarite
Ability: Levitate/Shadow Tag
Nature: Bashful
EV: 252 Spe/252 SpA/4 HP
-Sludge Bomb
-Shadow Ball
-Hex
-Destiny Bond

Gardevoir@Leftovers
Ability: Trace
Nature: Timid
EV: 252 Spe/ 252 SpA/ 4 SpD
-Synchronoise
-Destiny Bond
-Will'O'Wisp
-Light Screen

I wanted Chansey and Skarmory to cooperate in defense: Chansey as special wall, and Skarmory as a physical one. Also, Skarmory would be the lead of my party to set up entry hazards, and Chansey would work as a clerk. My offense is composed of mega Gengar (that I hope can be a special sweeper) and a physical Lucario. I think Gengar's hex would work well with Chansey's Toxic or Gardevoir's will-o-wisp. I wanted to make Gardevoir support, as opposed to a mega evolved attacker.

Also, I just cannot think of any pokemon to use as my last team member that would fit well and cover for the weaknesses of the others.
What changes do you suggest? Any help is welcome. Thanks in advance!

 

[PlatinumDude]

Adamant is pointless on Skarmory because it's meant to wall things, not attack. Impish is the better nature in this case.

Muscle Band isn't that useful compared to Life Orb and given Lucario's subpar defenses, the recoil damage of Life Orb doesn't really matter. Extreme Speed is also the superior priority move over Bullet Punch because it has +2 priority.

Mega Gengar is banned to Ubers. You'll need to make do with regular Gengar, which is still viable, in this case. Also, Hex is an inconsistent STAB to have because it relies on the opponent being statused. Here are better sets to run:
-Shadow Ball
-Sludge Bomb/Sludge Wave
-Focus Blast/Thunderbolt
-Destiny Bond
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb

or
-Substitute
-Shadow Ball
-Will-o-Wisp
-Taunt/Disable/Sludge Bomb/Sludge Wave/Focus Blast
Nature: Timid
EVs: 28 HP/148 SAtk/80 SDef/252 Spe
Item: Black Sludge

In the meantime, use Gardevoir as your Mega. Synchronoise, no matter how tempting the base power is, is utterly useless because it only hits Pokemon that share Gardevoir's type(s). Psychic resists Psychic, while Fairies are hit harder by Pixilated Hyper Voices:
-Psyshock
-Hyper Voice
-Focus Blast
-Taunt/Will-o-Wisp/Calm Mind
Nature: Timid/Modest
EVs: 24 Def/232 SAtk/252 Spe
Item: Gardevoirite
Ability: Trace

With the above set, Gardevoir can support while attacking. Taunt prevents setup from opposing walls (which is handy against stall), while Will-o-Wisp cripples physical attackers.

 

[Polar Spectrum]

Mate, if you're not playing by tiers and smog rules, and you're just doing battle spot, you can probably get away with half that if you really want to. Muscle band over life orb on Lucario can keep it from dying in a few circumstances due to the lack of constant recoil, Extreme Speed may be +2 Priority, but it isn't stab and can't hit super effective so bullet punch is a fine option especially with fairies about, Impish probably is better for Skarmory though considering it's only got 1 attack, but has both rocky helmet and roost. Your Mega Gengar seems like a quirky build, but you may want someone with Thunder Wave in your last slot to fill out your status setters with Chansey's toxic and Gardevoir's Will O Wisp on your team already if you do plan to use Hex, which I assure you can be very viable if given the right circumstance. However, I wouldn't recommend Shadow Ball and Hex - since it's kinda redundant :P Maybe Protect to scout a move, or rack up that toxic / burn damage from a teammate prior?

Edit: Oh yeah; but bashfaul on Gengar IS something you may wanna change hahah.