All right, Mint, start with Smokescreen and use Signal Beam and Dragon Pulse. But if he changes the weather to Rain, immediately change it to Hail and then Blizzard once or twice. If it's changed on the last turn, Disable him from using Rain Dance.

Smokescreen~Signal Beam~Dragon Pulse
Subs: Hail~Blizzard/Hail~Blizzard/Disable