Trying to Make a Balanced Team for Black/White

I haven't really battled competitively before and my knowledge on EV/IV training is nil, so I'm looking for advice on training a team with good balance between types, attack and support, etc. Thanks in advance ^^

Currently on my team:

Serperior
Nature: Bold
Held Item: Shell Bell
Ability: Overgrow
Moves: Giga Drain, Leaf Blade, Slam, Leaf Storm

My intent for Serperior was just to get a good balance, but I want to replace one of his moves with a support move such as Synthesis and maybe replacing Leaf Storm with Solarbeam.

Scolipede
Nature: Relaxed
Held Item: Rocky Helmet
Ability: Swarm
Moves: Steamroller, Strength, Rock Climb, Megahorn

This one is my physical attack powerhouse, and she has especially good defense and speed. Considering breeding for a replacement with Poison Point as an ability.

Chandelure
Nature: Serious
Held Item: Cleanse Tag
Ability: Flash Fire
Moves: Hex, Flamethrower, Flame Burst, Shadow Ball

My main special attacker, but her defense and HP are abyssmal. I also want a better hold item but I don't know what it should be.

Archeops
Nature: Timid
Held Item: None
Ability: Defeatist
Moves: Acrobatics, Fly, Dragon Claw, Rock Slide

This one's defense is also very low and his ability only makes it worse. Considering replacing with Mandibuzz or something else.

Galvantula
Nature: Serious
Held Item: Magnet
Ability: Unnerve
Moves: Gastro Acid, Bug Buzz, Volt Switch, Discharge

I usually use this one with Archeops in order to use Gastro Acid to cancel out Archeops's ability. Speed is excellent, defense is quite low again.

Jellicent
Nature: Sassy
Held Item: Quick Claw
Ability: Cursed Body
Moves: Surf, Ominous Wind, Waterfall, Water Spout

Speed is the worst here, all other stats are relatively high. Considering a replacement, but not sure what I would use.

Any advice is greatly appreciated. It doesn't matter to me what's banned and what isn't, since I don't do official tournaments or anything. Thanks again.

@Nytie; If you're planning on going deep into the metagame, I'd recommend going for Pokemon with better BSTs. As much as I wish I could say stuff like that doesn't matter, it does. :/

I'd be glad to give you more in-depth help on the basics of competitive play, so feel free to PM me if you wish. ^^

This looks more like an in-game team than one built for Wi-Fi battles. As such, I would recommend using this thread for such a team.