Pokémon Showdown: The Eagledome

Okay, I'll just have to advertise the Fail Cup.

Every pokemon in fail cup is pretty well balanced against each other. Even Beldum is weak to Burmy or Unown's HP Fire. Burmy is weak to Magikarp's bounce and other HP users, but it has Protect to defend against Bounce. Magikarp is the strongest sweeper, with Bounce and Hydro Pump, and highest speed, but it falls prey to Electroweb and Tynamo. Tynamo is possibly the most solid pokemon, with no weaknesses, though. The Bugs (Metapod, Kakuna, the Coons) all have a niche as a tank with Iron Defense, as well as Bug Bite to hit Wynaut and Unown, and Electroweb to hit Magikarp. Wynaut just might be banned, but it's not as strong here, honestly. Unown is a wild card, and it can fill up whatever move you need, and it will be a pretty strong move too, coming off the highest SpAtk in the tier. Combee has the most variety, with a bonus of gust, but it also has the most weaknesses. Kricketot has a few interesting moves like Bide and Uproar, but won't be all that useful. Ditto checks Burmy, Combee, and possibly Unown. Just don't use it on Wynaut.

You know what, here's a list:
Beldum
Unown
Burmy
Caterpie
Metapod
Weedle
Kakuna
Wurmple
Silcoon
Cascoon
Tynamo
Kricketot
Combee
Ditto
Magikarp