Help my team

I am going to play my Black 2 game again with a brand new team. But i'm stucking on some slots, so please give me your opinion.

For starter, i chose Snivy as I have never chosen it in the previous games.
1. Serperior @ Big Root
Ability: Overgrow
Jolly Nature
- Calm Mind
- Giga drain
- Leech seed
- HP [ Rock ]
I use HP [Rock] for coverage as it covers almost all weaknesses. I think Toxic for the last slot would be better but Toxic TM is a hard to get one in in-game.
However i'm planning to use a trick room team so Serperior might not be suitable. I'm just planning so I haven't tested yet.

2. Conkeldurr @ Flame Orb
Ability: Guts
Adamant Nature
- Dig / Rock Slide
- Ice Punch
- Drain Punch
- Knock Off
I use Conky because i'm using a trick room team. Good attack and pretty bulky. Ice Punch for coverage. Knock off for Ghost and Psychic type. Dig for electric coverage and in-game advanture. But I don't know if I should Use Rock slide instead of Dig .

3. Escavalier @ Leftovers
Ability: Swarm
Careful Nature
- X-scissor
- Iron head
- Reversal
- Slash
Another T-room sweeper with only 1 weakness. I can't get Megahorn for it because you need to breed to get it; therefore, X-scissor.

4. Bronzong @ Leftovers
Ability: Levitate
Impish Nature
- Bulldoze
- Trick Room
- Reflect
- Light Screen

5. Gothitelle @ Leftovers
Ability: Competitive
Relaxed Nature
- Psychock
- Thunder Bolt
- Trick room
- Shadow Ball
You should always have 2 T-room setters. But this Gothitelle is what I'm worried about. I really like it but I don't know which role should I use: Dual Screen or Tank or Sp.Attack… I also heard that Musharna is a better Psychic pokemon or the T-room set-up position. Chandelure or Reuniclus outclassed it too but I don't want to use Chandelure again and Reuniclus would make the game... too easy ? ( I can't get Reuniclus in Black 2 either )

6. Panpour / Jellicent / Swanna / Alomomola
This gen doesn't have lots of water type pokemon and I want a Water pokemon that is good for my team and works well with Surf. Right now, I'm thinking of Swanna because of its typing that can help you with both Surf and Fly. But Jellicent is OK too with Ghost typing, pretty bulky and slow speed for T-Room.~_~

I'm not really good at planning teams; therefore, i realized that my team has big weakness to Fire, Ghost and Dark.
The biggest threats are Cofagrigus, Chandelure, Spiritomb... anything that has low speed. But I just don't know how to fix it.
So please give me some advice. This is my very first In-game Trick room team.
Any suggestions would be awesome.

Alomomola could have been a good option for slot number six, as one of its abilities allow the Pokémon to recover a decent portion of its health ever time it switches out, but this is in-game we're talking about, however, where we are freely permitted to utilize recovery items. Due to this, none of its might not be too necessary.

Personally, I would likely go with Swanna. Since it's partially flying-type, it could learn the move Fly without any block, which might be important to visit places. When it comes to battling, Fly could also be pretty useful; it's not a weak attack.

Aside from above, Jellicent would be another good choice, I believe. This Pokémon has good defenses, and could make a nice wall for almost any team. On top of this, Jellicent would have chance to withstand a lot of fire-type hits Serperior and Bronzong might be thrown, which is a plus!