Look at these rules...

So, my friends and I started having tournaments a few months ago. I came up with the idea that whoever was hosting the tournament would come up with the rules. Since I came up with the idea I hosted the tournament and made the rules. My rules were simple, OT, no psuedos, no legends, no items, just to get the ball rolling because none of us had actually battled before. The first tournament came it was all good, two out of the six of us weren't prepared... We went with it, and we deemed a winner who literally swept us all. He then created a new set of rules, which were very similar to mine. Except when his tournament came only me and him were prepared... He passed off hosting duties to another one of our friends here are his rules... 1) Your party must consist of fire, water, grass, dark, fighting, and psychic Pokemon. Dual typing is allowed. 2) One legendary is allowed.

Personally I don't like these rules, because your party must have certain Pokemon, and it leaves out many others. I also am opposed to using legendaries; I don't mind psuedos, but I don't like legendaries at all.

What do you think of these rules? And any ideas for a dark pokemon? :)

I don't mind the first rule as long as the six share good synergy with one another, but it's a bit restrictive at the same time because you don't get to use Pokemon like Excadrill and Scizor. I don't mind the second rule either.

I know you're against the use of legendary Pokemon, but not all legendary Pokemon are good. For instance, look at Articuno and Entei. They have good stats, but they lack the move pool to abuse them. Also, look at Cobalion. It and Lucario share the same typing, but Lucario is better at sweeping because of a wider move pool and higher offenses. What Cobalion has over Lucario are higher defenses and Speed at the cost of lower offenses and a smaller move pool.

And as for your Dark Pokemon: use Hydreigon. Even though Tyranitar can be used, it hinders the team with its Sandstream ability if you don't have Pokemon immune to sandstorm:
-Draco Meteor
-Fire Blast/Flamethrower
-Focus Blast
-U-turn
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Scarf

If you really want to use Tyranitar, be my guest:
-Stealth Rock
-Crunch
-Fire Blast
-Ice Beam/Superpower/Stone Edge
Nature: Sassy/Hasty
EVs: 252 HP/64 SAtk/192 SDef (Sassy) or 56 Atk/252 SAtk/200 Spe
Item: Leftovers
Ability: Sandstream

It would also be nice if you posted the team you intend to use.

Hmm yeah good point on the legends. I might try the Hydriegon. I will post the rest of my team once I figure out what I'm going to use... The only one I'm sure on is Empoleon
Empoleon
Ice Beam
Grass Knot
Agility
Hydro Pump
Nature: Modest
EVs: 16hp 252 Spatk 240 SPD