3rd Gen What should my 6th Pokémon be? [Nuzlocke]

[iaMiro]

I am doing my first Nuzlocke challenge for the ROM hack, Omega Fire Red [Please don't spoil anything for me :)]. I have been training for the elite 4 and I'm assuming they'll all be in the Lv 70 - 80 range for the first time around.

The 5 Pokémon I currently have with approximate EVs:
Kingdra [240HP, 252 SpA,16 Spe] [Rain Dance, Surf, Ice Beam]
Forretress [252HP, 252 SpD] [Spikes, Rapid Spin, Toxic?]
Starmie [252SpA, 252 Spe] [Surf, Psychic, Ice Beam, Thunderbolt]
Mr Mime [252HP, 80SpA, 10 SpD, 166 Spe] [Calm Mind, Baton Pass, Psychic, Encore/Subsitute]
Gyarados [100HP, 252 Att, 156 Spe] [Dragon Dance, Earthquake, Hydro Pump/Surf, Thrash/Double Edge]

Now because this is Omega Fire Red, I am able to get evolutions that normally need to be traded, but cannot get extra items/tms.
I plan to give Calm Mind to Mr Mime to make him a baton passer.
I have already used Psychic on Starmie.
I plan to give Rain Dance to Kingdra.
I plan to give Earthquake to Gyarados.
I plan to give Toxic to Forretress.
I'm considering to give Substitute to Mr Mime unless I'm giving it to a SubPuncher.

Any breed moves are out of the question for this challenge.
After a tragic loss of both my Dragonair and Tyranitar, I'm at a loss for what my 6th Pokémon should be for this team!
What would you recommend from this list? [All at 0 EVs]
Jumpluff
Lunatone
Clefable
Dewgong
Smeargle
Raichu
Magneton
Ninetails
Rapidash
Arcanine
Miltank
Tentacruel
Gengar
Walrein
Crobat
Weezing
Victreebell
Sunflora
Seaking
Granbull
Dodrio
Xatu
Golduck
Gorebyss/Huntail [This is a 50/50 on what it would evolve into.]

I'm thinking of grabbing Smeargle so I can do a Calm Mind Baton pass from Mr Mime into an ingrain + substitute baton pass from Smeargle. Maybe spore along with it, giving a Starmie or other special sweeper a great setup. Also the Smeargle pass to my physical Gyarados could set up for a few Dragon Dances, allowing a physical sweep.
Though I'd probably give him 252 HP, 252 Spe EVs, I would still be worried about how fragile he is for a Nuzlocke, but as long as I play it right, I think he could be good...

Lightly considering a few others, but what's your recommendation?

 

[Brendino]

I'm guessing all the Pokemon that you've listed are the ones that you've caught along your journey, right? Anyway, if it were me, I'd probably want something that balanced out the 3 Water types on the team- maybe an Arcanine or a Victreebel of the ones from your list. Smeargle wouldn't be a bad option either, with an endless amount of possibilities for its moveset, despite its less than ideal stats.

I'm not huge into competitive style battling though, so maybe there are other Pokemon there that are better options based on weaknesses and resistances, but that's just my two cents!

 

[Sektor]

I second the Victreebel. Can't go wrong with acid. Arcanine is also a prime contender. I'd go with Arcanine first if possible. It's one of the toughest Fire Type Pokemon on the market.

 

[classiccartoonsftw]

By the looks of your team, you're gonna have trouble with Electric and Dark types. I'd recommend a Ground or Fighting type, but I don't see any on your Pokemon list. Your best bet is probably Granbull, which could make a nice SubPuncher.