So, the goal to beating Rain teams have 2 paths. One tip I usually keep in mind is don't try to outsweep the sweepers. Try to outlast them and wear them down.
1. Take down the Rain Setter
2. Take down the Rain Sweepers
I will take you through the 2nd method first. Now, just like the comments say, Tangrowth is a great option to counter Rain Teams and I know this from Experience. Fortunately for us, many Rain Sweepers like Crawdaunt, Barraskewda and sometimes Seismitoad are physical attackers. Additionally, Tangrowth doesn't worry about any of them due to its Physical Bulk. There is only a slight problem that Tangrowth will face though. This is a Special Seismitoad and a Pelipper. These 2, especially Pelipper, will rip right through Tangrowth. I propose a solution though, don't try to fix its Special Defense, but instead, buff its Physical Defense and combine this with a Rocky Helmet to get a Physical Killer that doesn't mind any Physical Rain Sweepers. My proposed set.
Tangrowth @ Rocky Helmet
Regenerate Ability
252 Def/252 HP/4 SpD
- Giga Drain
- Knock Off
- Focus Blast
- Sleep Powder
Now, this is only half the problem, we still have Special Sweepers a Pelipper to deal with. My idea as a solution is Rotom-W. Rotom doesn't mind anything from Seismitoad except for a Poisoning from Sludge Bomb. Rotom-W also has nice bulk to pressure any Frail sweepers and force a switch. Due to this, you can also provide offensive presence with a boosted Hydro Pump and Will-o-Wisp to provide a deterence to any Physical Sweepers. My proposed set -
Rotom-W @ Leftovers
Levitate Ability
252 HP/152 SpD/48 Spe/56 SpA
Calm Nature
-Volt Switch
-Thunderbolt
-Hydro Pump
-Will-o-Wisp.
This combination of Tangrowth and Rotom-W should provide defense and pressure against Rain teams and I hope you find Success with it. The only threat against these 2 mons is Thunderus-Therian, but I believe that the rest of your team should cover it fairly well. Rotom-W also covers the 1st method of beating a Rain Team, by beating the Rain Setter. If you want another method, you could try another weather setter or even put something like Ferrothorn on your team to take advantage of Rain while still having a solid Pokemon to use.
Hope this helps!
