Heysup's Helpful Awesome Guide to beating Rain Dance:
- USE A LEAD THAT IS FASTER THAN ELECTRODE WITH SLEEP POWDER OR TAUNT. This may seem stupid because it usually, well, always means that you will need to Scarf something, but the best way to stop Rain Dance is to not let them set up.
- Have another Pokemon faster than Uxie with Taunt so that they cannot switch to their second Rain Dance set up and get Rain up (this is likely Uxie or Registeel, and Uxie is the faster one). (Amibpom, Froslass, etc).
- Use at least one Pokemon that resists Ice, and one Pokemon that resists Water (that isn't OHKOed by stuff). This will help you exponentially in stalling out the opponent's Rain Dance. Additionally, if you predict correctly you can even Paralyze the opponent with something like Slowbro.
- Use Slowbro. Fuck Kabutops. Fuck Qwilfish. It's also not useless in other battles.
- Registeel helps.
- Use Fake Out, Protect, etc. on what ever Pokemon it makes sense to do so on, or choose Pokemon that use Fake Out. For example, use Wish + Protect on Clefable instead of Stealth Rock + Softboiled. Fake Out is especially good; not only does Fake Out damage the opponent, but it stalls a turn of rain. Technitop, Ambipom, and others come to mind.
- Use priority, especially Vacuum Wave. Most RD sweepers are lolweak to Special Fighting attacks, and Vacuum Wave from something like Blaziken or Toxicroak hurt them like hell. They OHKO Kabutops (careful when using Blaziken), Omastar, and do a hefty amount to Gorebyss. Watch out for Qwilfish though.
- Make your turns count. If the opponent does NOT have Rain Dance up, make sure to take this opportunity to destroy as much of their team as possible. This shouldn't be hard since without Rain they are just a slow and frail offensive team. It helps to use Pokemon like Raikou here, since it hits every Rain Sweeper SE besides Ludicolo.
- Ban Kabutops.
Yea, most of these are common sense but really people seem to be forgetting how to play rain just because Cresselia is around.
Note: You do not need to run all of these to beat Rain, they are just there as examples of what can help you beat rain.