I really don't like Pokebeach's for one reason: The forum is full of...young players (see, I found a way to say it unoffensively! You should all know what I mean by that.) PokeGym actually has a handful of good, intelligent players that play the gameboy games, so I think a league would work well here.
With that in mind, I'd like to propose an idea that I proposed on PokeBeach that people received with mixed feelings.
A realistic Gym League.
Gym Leagues, as you know, are leagues where people are appointed as Gym Leaders, and challengers that beat them win "badges" and prized. However, on Pokebeach and Serebii and other forums, the Pokemon used in the Gym Leagues are all Level 100 Pokemon. But in the gameboy games, the gyms start at level 10 and get progressively harder. We should make a league like that - the first Gym is low level (10 or 15), and the last gym is level 100. Obviously, there would be 17 gyms, one for each type.
Now, to balance this out, the challenger's Pokemon could be no higher a level than those of the leader they were facing. This makes it realistic too, you can breed your ideal team, start them at level one, and fight gym leaders on wifi as you make them stronger off of wifi. Also to make it more realistic, you can't battle gym 2 until you beat gym 1, you can't battle gym 4 until you beat gym 3, etc. We could keep a master list of the Gym Leaders and who has beaten them to prevent cheating like this.
Here's the setup I proposed over there, but we can all brainstorm if we want the types/levels to be distributed differently:
Gym1: Lv.15 - Bug
Gym2: Lv.20 - Rock
Gym3: Lv.25 - Flying
Gym4: Lv.30 - Poison
Gym5: Lv.35 - Normal
Gym6: Lv.40 - Fighting
Gym7: Lv.45 - Electric
Gym8: Lv.50 - Ice
Gym9: Lv.55 - Ground
Gym10: Lv.60 - Dark
Gym11: Lv.65 - Grass
Gym12: Lv.70 - Fire
Gym13: Lv.75 - Water
Gym14: Lv.80 - Ghost
Gym15: Lv.85 - Steel
Gym16: Lv.90 - Psychic
Gym17: Lv.100 - Dragon
So what do you guys think?