Team building Ideas and Suggestions?

So I am trying to build a competitive'ish team. Mostly to fight online and harass my roommate with awesomeness.

I am mostly doing breeding and now have a new pool of pokemon to work with thanks to pokebank and some friends giving me their pokemon games.

I've scrounged together the IV bred pokemon from the games which gives me some that are ready now.

Arcanine LvL100
31/31/31/31/31/31
HP 339/ATK 350/DEF 196/SP.ATK 212/SP.DEF 198/SPD 270
Flare Blitz, Extreme Speed, Wild Charge, Close Combat

Mawile LvL63 (Still leveling, but her EV's are done pretty much.)
31/31/31/31/31/31
HP 188/DEF 131/SP.ATK 83/SP.DEF 93/SPD 88
Sucker Punch, Play Rough, Swords Dance, Super Fang

Jolteon LvL100
31/31/31/31/31/31
HP 148/DEF 156/SP.ATK 319/SP.DEF 226/SPD 394
Thunderbolt, Volt Switch, Signal Beam, Hidden Power

Alakazam LvL100
31/31/31/31/31/31
HP 252/ATK 122/DEF 126/SP.ATK 369/SP.DEF 226/SPD 372

Gengar LvL100 (I have 4 of these so I can set up different move sets. Only 2 are at 100 though)
31/31/31/31/31/31
HP 263/ATK 149/DEF 156/SP.ATK 358/SP.DEF 186/SPD 350
Sludge Bomb, Shadow Ball, Hypnosis, Dream Eater
&
Shadow Ball, Protect, Perish Song, Substitute

Sableye LvL100
31/31/31/31/31/X
HP 304/ATK 167/DEF 216/SP.ATK 166/SP.DEF 220/SPD 136
Recover, Will-O-Wisp, Taunt, Night Shade

Muk LvL100
31/31/31/31/31/31
HP 414/ATK 339/DEF 186/SP.ATK 149/SP.DEF 237/SPD 136
Substitute, Focus Punch, Poison Jab, Ice Punch

I also have a Leafeon a friend gave me, he said she was all 31, but haven't checked yet. I am currently working on breeding out a perfect Goomy, Honedge, Pumkaboo (I just like pumkaboo), Noibat, and Shuppet.

So far I've just collected and bred pokemon I like, though I want to build a functioning team, so I'd like some feed back on pokemon I NEED to form a rounded team. I'd like to keep Gengar on my team though, it was a ♥♥♥♥♥ to make him from scratch.

There seriously is no need to say your Pokemon's IVs and stats. Only natures and EVs matter in this forum.

Arcanine honestly isn't that good; sure, it has a wide move pool, but there are Fire Pokemon who can do its job better, i.e. Talonflame, Volcarona, Entei and Heatran:

Talonflame:
-Swords Dance
-Flare Blitz
-Brave Bird
-Roost
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Life Orb/Sharp Beak/Sky Plate
Ability: Gale Wings

or
-Flare Blitz
-Brave Bird
-U-turn
-Tailwind/Roost
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Choice Band/Sharp Beak/Sky Plate
Ability: Gale Wings

or
-Bulk Up
-Brave Bird
-Roost
-Taunt/Substitute
Nature: Careful
EVs: 248 HP/184 SDef/76 Spe
Item: Leftovers
Ability: Gale Wings

Volcarona:
-Quiver Dance
-Fire Blast/Fiery Dance
-Bug Buzz
-Hidden Power (Ground/Rock)/Giga Drain/Psychic
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb/Lum Berry
Ability: Flame Body

or
-Quiver Dance
-Fiery Dance
-Bug Buzz
-Roost
Nature: Timid
EVs: 240 HP/252 Def/16 Spe
Item: Leftovers
Ability: Flame Body

Entei:
-Sacred Fire
-Extreme Speed
-Stone Edge
-Bulldoze
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Choice Band

Heatran:
-Lava Plume
-Protect
-Roar/Earth Power
-Toxic/Stealth Rock/Will-o-Wisp
Nature: Calm
EVs: 248 HP/8 Def/252 SDef
Item: Leftovers
Ability: Flash Fire

or
-Fire Blast
-Earth Power
-Hidden Power (Ice)/Stealth Rock
-Will-o-Wisp/Toxic
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Air Balloon/Leftovers
Ability: Flash Fire

or
-Fire Blast/Overheat
-Flash Cannon
-Earth Power
-Hidden Power (Ice)/Flamethrower
Nature: Timid/Modest
EVs: 252 SAtk/4 SDef/252 Spe
Item: Choice Specs/Choice Scarf
Ability: Flash Fire

or
-Magma Storm
-Toxic
-Taunt
-Protect
Nature: Calm
EVs: 248 HP/252 SDef/8 Spe
Item: Leftovers
Ability: Flash Fire

There are better Electric Pokemon out there than Jolteon, like Wash Rotom. Jolteon's move pool is rather shallow:

Wash Rotom:
-Volt Switch
-Hydro Pump
-Will-o-Wisp
-Pain Split/Rest
Nature: Bold
EVs: 248 HP/216 Def/44 Spe
Item: Leftovers

or
-Volt Switch
-Hydro Pump
-Thunderbolt/Pain Split
-Will-o-Wisp
Nature: Modest
EVs: 228 HP/60 SAtk/220 Spe
Item: Leftovers

or
-Volt Switch
-Hydro Pump
-Thunderbolt/Hidden Power (Ice/Fire)
-Trick
Nature: Timid/Modest
EVs: 4 Def/252 SAtk/252 Spe
Item: Choice Scarf

I don't think Mega Mawile needs Super Fang. It's already crazy strong enough that its moves can strip off more than half of the HP of most opponents, if not OHKOing them:
-Play Rough
-Sucker Punch
-Fire Fang/Iron Head/Swords Dance
-Swords Dance/Substitute
Nature: Adamant
EVs: 132 HP/252 Atk/124 Spe
Item: Mawilite
Ability: Intimidate

or
-Rest
-Sleep Talk
-Play Rough
-Foul Play
Nature: Impish
EVs: 252 HP/252 Def/4 SDef
Item: Mawilite
Ability: Intimidate

Alakazam is best played as an all-out attacker:
-Psychic/Psyshock
-Shadow Ball
-Focus Blast
-Hidden Power (Ice/Fire)/Dazzling Gleam
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Focus Sash
Ability: Magic Guard

Mega Gengar can perform Perish-trapping better, but Gengarite is banned in the standard (OU) environment; it's okay to use in Wi-Fi battles, though. Since your Mega slot is taken up by Mawile, don't bother with Mega Gengar; instead, use Gengar's regular form:
-Shadow Ball
-Sludge Bomb/Thunderbolt
-Focus Blast
-Destiny Bond
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb

or
-Substitute
-Shadow Ball
-Disable/Pain Split/Will-o-Wisp
-Will-o-Wisp/Pain Split/Focus Blast
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Black Sludge/Life Orb

or
-Shadow Ball
-Sludge Bomb
-Focus Blast
-Trick/Thunderbolt/Hidden Power (Ice)
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Scarf

Sableye should use Calm or Careful with this:
-Taunt
-Will-o-Wisp
-Recover
-Foul Play/Knock Off
Nature: Calm/Careful
EVs: 252 HP/4 Def/252 SDef
Item: Leftovers
Ability: Prankster

Muk is seriously outclassed by other Pokemon. It has a wide move pool, sure, but I think that there are other Pokemon who are much more useful in its place. Instead, make do with a Rapid Spinner/Defogger to control your entry hazards:
Starmie:
-Hydro Pump/Surf
-Thunderbolt/Psyshock
-Ice Beam
-Rapid Spin
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Leftovers/Life Orb
Ability: Natural Cure

or
-Scald
-Rapid Spin
-Psyshock/Ice Beam/Thunderbolt
-Recover
Nature: Timid
EVs: 248 HP/32 Def/4 SAtk/224 Spe
Item: Leftovers
Ability: Natural Cure

Excadrill:
-Earthquake
-Rock Slide/Iron Head
-Rapid Spin
-Swords Dance/Stealth Rock
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Leftovers/Air Balloon/Chople Berry
Ability: Mold Breaker

or
-Earthquake
-Iron Head
-Rock Slide
-Rapid Spin
Nature: Adamant/Jolly
EVs: 120 HP/136 Atk/252 SDef (Adamant) or 252 Atk/4 Def/252 Spe (Jolly)
Item: Assault Vest (Adamant)/Choice Scarf (Jolly)
Ability: Mold Breaker

Mandibuzz:
-Foul Play
-Roost
-Defog
-Toxic/Whirlwind/Knock Off
Nature: Bold/Impish
EVs: 248 HP/252 Def/8 SDef
Item: Leftovers
Ability: Overcoat

Crobat:
-Brave Bird
-Defog
-Roost
-Taunt/Toxic
Nature: Jolly
EVs: 168 HP/136 Atk/4 SDef/200 Spe
Item: Black Sludge
Ability: Infiltrator

Tentacruel:
-Scald
-Sludge Bomb
-Rapid Spin
-Toxic/Knock Off
Nature: Bold
EVs: 252 HP/224 Def/32 Spe
Item: Black Sludge
Ability: Liquid Ooze

Also consider a hazard setter on the team, like these:
Ferrothorn:
-Stealth Rock/Spikes
-Leech Seed
-Gyro Ball/Thunder Wave
-Power Whip/Protect
Nature: Relaxed
EVs: 252 HP/48 Def/208 SDef
Item: Leftovers
Ability: Iron Barbs

Skarmory:
-Roost
-Whirlwind
-Stealth Rock/Spikes/Brave Bird
-Defog/Brave Bird
Nature: Bold/Impish
EVs: 252 HP/252 Def/4 SDef or 252 HP/16 Def/240 SDef
Item: Leftovers/Rocky Helmet
Ability: Sturdy

or
-Spikes
-Roost
-Whirlwind
-Taunt/Brave Bird
Nature: Bold/Impish
EVs: 252 HP/184 Def/72 Spe
Item: Leftovers/Rocky Helmet
Ability: Sturdy

PlatinumDude said:

There seriously is no need to say your Pokemon's IVs and stats. Only natures and EVs matter in this forum.
(Snip)

Click to expand...

I just got home so am going to bed, but thanks for all the info! I'll pick through what I have and use this to build a better team. The ones I put up are not my team they're just the best I currently have. Last night I spent 8 hours during work just breeding Goodras XD I got them to 5/6 stats at 31 steadily, just tryin to find a good build on it. Any suggestions? Mostly they're Quiet Natures.

Dizzie said:

I just got home so am going to bed, but thanks for all the info! I'll pick through what I have and use this to build a better team. The ones I put up are not my team they're just the best I currently have. Last night I spent 8 hours during work just breeding Goodras XD I got them to 5/6 stats at 31 steadily, just tryin to find a good build on it. Any suggestions? Mostly they're Quiet Natures.

Click to expand...

Goodra is one of the best Assault Vest tanks out there:
-Draco Meteor
-Fire Blast
-Thunderbolt/Sludge Bomb/Dragon Tail
-Earthquake/Dragon Tail
Nature: Quiet/Sassy
EVs: 248 HP/252 SAtk/8 SDef
Item: Assault Vest
Ability: Gooey/Sap Sipper