1. Anti-weather ability pokemon- reverse all effects of weather and weather based abilities while this pokemon is on the field. IE, sandstorm deals damage to rock, ground, and steal types, while previously injured types are spared, spc def for those types are reduced instead of increased, chlorophyll slows the pokemon down to 1/2 speed in sun with boost to water moves, redux in fire atks, moves that would normally 100% in that weather would have a chance to injure the user instead (only as much as hurting itself in confusion), etc. I would suggest this as an evolution of castform, and thus normal typed. Really, this is the big FU to weather teams that I really want. I figure the ability should be be called- Inclement Weather, or Odd Forecast or something ominous.
2. Pokemon with ability that is basically auto-snatch. Dragonite used DragonDance but [new pokemon] stole the effect and now [new pokemon]'s speed and attack are raised! I see you setting up and I like your style, so imma steal it. I'm thinking this should be a steel/pychic type mirror-looking/related pokemon. Alternatively, think Serperior, but instead of perversity working on itself, it works on opponents, so calm mind reduces instead of buffs. This is probably less broken than stealing effects outright. Maybe expand scope to steal or reverse abilities like speed boost. Breaks the whole annoying, protect pass/uturn strategy of gayness.
first proposition is anti-weather. second is anti-setup.
3. Random weather pokemon- suggested alternate evolution to Castform, this pokemon randomly changes the weather to a random weather state other than the current one. IE, if it is raining, the weather will randomly change to sandstorm, hail, sunny, or neutral but it cannot remain raining. Perhaps toss in the 50% chance that a change to neutral weather will include trick room status as well.
proposition 3 is also anti-weather.
The moral of the story is, reliance on weather is lame. It started off as fun, but then b/w broke it. Time to fix it.