I'm a few days late, but better late than never.
You'll need a Water-type with Ice Beam do deal with Grass-type Pokemon.
Jellicent is a nice one with bulky Sp. Def and HP. Recommended nature would be Modest since its attacks are more Special-based, a moveset I suggest for it would be Ice Beam, Surf, Shadow Ball and Toxic/Attract.
Cursed Body is a nice ability for Jellicent as it has a chance of disabling an opponents attacks.
Attract is good if you get a female one since most opponents (as you said) would be male.
For a good Fire-type attacker, I suggest you should try Darmanitan - its attacks that cause beneficial secondary effects naturally are increased in power due to Sheer Force (although you lose the secondary effect). It has a high Attack stat too so I recommend a Physical-based moveset and the nature I recommend is Adamant since Darmanitan's Sp. Atk is very weak and Adamant nature boosts Attack. A good moveset should be Earthquake, Flare Blitz, Hammer Arm/Brick Break and one other random attack.
Hydreigon is a good Special attacker, I have one with a Docile nature that currently knows Acrobatics, Dragon Pulse, Crunch and Flamethrower. The reason mine is balanced between Physical and Special is because of the Docile nature.
I love using my Hydreigon in the Battle Subway and she literally slays a lot of opponents (except Dwebble and Crustle due to X-Scissor).
If you want to invest in Hydreigon, Dragon Pulse is a must-have move. Dark Pulse can only be obtained by breeding with a Gyarados, Ekans, Arbok or Seviper that has learned the move in Gen IV and sent by Poke Transfer. It's a bit fiddly, so I don't recommend Dark Pulse.
Seviper is in both the Field and Dragon egg groups, so you can still do the Dark Pulse breeding trick by getting a male Smeargle to Sketch Dark Pulse, breed with a female Seviper and if the offspring Seviper is male, breed with a female Deino/Zweilous/Hydreigon and you still might get that Dark Pulse Deino.
Smeargle are found on Route 5 during swarms, while Seviper can be caught at Village Bridge.
I recommend Dragon Pulse, Crunch (assuming it's a Hardy, Docile, Bashful, Serious or Quirky nature) and two random moves to counter it's weaknesses.
Eelektross is also one to look at, it's very balanced between Physical and Special Attacker plus it has a wide movepool and Levitate ability. Some moves I recommend are Thunderbolt, Acrobatics, Flamethrower, Flash Cannon, Dragon Claw, Brick Break and Rock Slide plus there's Crunch if you like. It all depends on the nature of your Eelektross if you should invest in Special or Physical moves.
And remember, TM Moves is where Eelektross shines and because in B/W TMs can be reused, so you switch Eelektross' moveset as often as you like. It's definitely something with capabilties, Speed is its only low point but you have no weaknesses to worry about (just watch out for Smack Down as that move disables Flying-type and Levitate ability)
Physical Attacker natures for Eelektross: Adamant, Brave, Naughty, Lonely, Jolly, Careful, Impish
Special Attacker natures for Eelektross: Modest, Mild, Rash, Quiet, Timid, Bold, Calm
Mixed Attacker natures for Eelektross: Any nature not listed above
And as Keiran and I mentioned, you have a massive Fire weakness so you need to change around a bit. You could go with what I mentioned, although Keiran should suggest going with Kingdra as it has only one weakness and a good moveset would be Ice Beam, Dragon Pulse, Rain Dance and a Water-type attack for STAB.
Also, as Keiran said Steel/Bug Pokemon like Scizor and Escavalier and also the Grass/Steel Ferrothorn can also be trouble for you.
Chandelure is a great Special attacker but has 5 weaknesses. If you plan on using a Chandelure, counter its weaknesses if you can. Energy Ball is great cos it's a Grass-type move and can counter Chandelure's Rock/Ground/Water weakness. Shadow Ball and Flamethrower for STAB and to deal with Dark-types, invest in a Fighting or Bug Hidden Power.
Or you can try getting an Infernape via Poke Transfer cos it's popular in competitive play, it's fast and hits hard. A good Infernape moveset is Flamethrower (STAB), Focus Blast/Brick Break/Close Combat and probably Grass Knot and Earthquake/Stone Edge. I recommend a Naive nature for that extra Speed.
It's all up to you!
Kingdra takes almost no Fire damage, especially in rain, so swap whenever you are predicting a Fire attack.
*shrug* I can't see any other special sweeper working well with your team. Chandelure would be the next best, I think, but it has a lot of weaknesses and doesn't complement the rest of your team well.
Make sure to suggest things in the proper tier. If you aren't sure, this would be a good place to consult.