Ooh, how about a Dark type Gym? never seen one of those!

Team: Drapion, Hydreigon, Zoroark, Houndoom, Spiritomb, 

Either Dark or Electric Types. I love both types~! ^^

I would have a physic/grass type gym, lets see if ash can't beat any level 100 pokemon.
Pokemon are:
level 66 unknown pokemon
level 77 mew
level 99 mewtwo
level 100 unevolved pichu

Lets see if ash can't beat any trainers now!

It would be between Dark and Psychic types

Mewto would have to be my Fav Pokemon right behind Pikachu though.! Pika should be everyons favorite pokemon.

I would choose dragon because of the wide variety of different type combinations and very strong pokemon. my six pokemon would probably have to be, excluding legendaries of course, dragonite, kindra, salamence, garchomp, haxorus and druddigon.

I would have normal types like snorlax and others like that

Mine would all be dark type.

Go umbreon and tyranitar! Go!

tuskegee2014 : LOL, I'd just get a ton of Mewtwo and try to get a lot of coins in the actual games.

My Pokémon gym would be mixed of fire, water, flying, grass, ghost, and electric. If it had to be only one type it would consist of moltres, infernape, heatran, houndoom, charzard, and Flareon.

I would make my own brand of pokemon that were really transformers. That's the kind of Gym I would have.

But seriously mine would all be Dark type

My Gym would most certainly be a Bug type gym. For one simple reason: There are very diverse types of bugs. For example Ninjask is Flying/Bug. My gym would also be like a Maze that way it'd be annoying for trainers. The five Pokémon I would have and with their moves are:

1. Forretress. (Bug/Steel)    I would choose this one first simply for the spikes. Building spikes is a very annoying tactic.
Moves: Spikes, Toxic, Earthquake, Explosion

2. Ninjask.   (Bug/Flying)   Ninjask isn't very good but the first attack is always his. Plain and simple spamming confuse ray.
Moves: Fury cutter, Confuse ray, Aerial Ace, Fly.

3. Pinsir. (Bug) Pinsir is just plain strong. His attack is massive and he can do tons of damage especially with swords dance.
  Moves: Swords Dance, Guillotine, Submission, Brick Break.

4. Shedinja. (Bug/Ghost)   Yes he has 1 hp. But only super effectives' can hit it and with confuse ray and double team it would be hard to knock it out.
Moves: Destiny bond, Shadow Ball, Double Team, Confuse Ray

5. Shuckle. (Bug/Rock) To put it plain and simple shuckle has more defense than any other non legendary. He has absolutely no offense but he can sure outlast your Pokémon. Shuckle would defiantly be my gyms best.
Moves: Toxic, Confuse ray, Rest, Sandstorm.

If this gym wouldn't give you a hard time I don't know what would.

Mine would be a Legendary Pokemon gym, yeah, Awesomely awesome!

Mine would be a toss up between Dark and Steel typing. I love Dark type, all of them. With beasts such as Tyranitar, Weavile and Umbreon, it's tough to defeat. As for the Steel, there are a few Steel types I am really fond of, mainly Scizor.

I would choose Dark. My Gym obstacle would be a mix of Brawly's and Morty's, just to mess with people. It is pitch black with only a small circle around you, but it never grows. Plus, when you step off the 'invisible' path, you get warped to the front again. Muwahahahahhaha.

As for team, I'd like my team to be preferably late game, so 7th or 8th badge. It'll give me time to make sure my team can be fully evolved.

Weavile:
Swords Dance, Ice Shard, Night Slash, Pursuit.
Not only is he insanely fast, but Swords Dance and Ice Shard make a potent priority attack. And Pursuit for when you try to switch.

Zoroark:
Nasty Plot, Dark Pulse, Flamethrower, Focus Blast
This is one of my main attackers, with high stats, plus his ability lets me switch in on a not very effective hit.

Drapion:
Night Slash, Pursuit, Earthquake, Aqua Tail.
With Sniper and Night Slash, a critical hit may wipe you out.

Krookodile:
Crunch, Earthquake, Stone Edge, Pursuit
With Moxie, even killing 1 of your Pokemon allows me the chance to sweep.

Houndoom:
Nasty Plot, Dark Pulse, Flamethrower, Hidden Power (Grass)
As my strongest, he can cover a good amount of types, Nasty Plot always helps.

I built my Gym team around my personal play style. I am not one to sit around and tank, stall, and poison my way to victory. I strike hard, I strike fast. I don't choose Pokemon that can take a hit and give one back. I choose Pokemon that have good offensive stats, and can get the first strike.

I would have a gym with the type being steel, because they are very hard to kill, especially because of their resistance to burns poison, and stun. <- all making them very powerful, oh not to mention their defense, they have killer defense as well. Just great pokemon.

my gym type pokemon would be fire because fire type pokemon are strong and i would have charizard and blaziken would be my strongest pokemon and that's my pokemon gym badge and the badge would be called the blaze badge

I would run a combination of Psionic-/Psychic-types and Glitch Pokémon.

Mine gym would be a Dark and Ghost type gym like Morty in Pokémon Gold, Silver, Crystal, Heart Gold, and Soul Silver

Mine would be half fire half fighting gym.

I'd most likely go with poison type.
Lots of double typings in many poison type pokemon would be useful, and with levitating/flying types ground would be uneffective + drapion to take care of psychic types. (Also poison pokemon are just really cute and always on my team in every game.)