Hello! I have a few thoughts.
Politoed is usually considered much better on rain teams in VGC, because your sweeper has Swift Swim which already doubles your speed, so Tailwind is usually unnecessary, and Politoed has a much better support movepool than Pelipper with Helping Hand, Hypnosis, Perish Song and Icy Wind. I strongly recommend Politoed, but Pelipper is fine.
Next, Ludicolo. Since it’s pretty lacking offensively, what I’d do is change it to a weakness policy set. You can have a Scarfed Mon, which will almost certainly be the fastest thing on the field, U-Turn into Ludicolo and switch into Politoed, which will set the rain and make Ludicolo the fastest. (Watch out for Tailwind.)
Ludicolo @ Weakness Policy
Ability: Swift Swim
Level: 50
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Giga Drain
- Hydro Pump
- Blizzard
- Protect
When Dynamaxing it, be very aware of clicking Max Hailstorm because of overwriting the rain.
EDIT: Something funny you could do is eject button Politoed. This will make it switch out without having to waste a turn (assuming it gets hit), making it easier to use Max Hailstorm.
Blizzard allows you to OHKO Dynamax Dragapult with Max Hailstorm at +2, and Hydro Pump will most likely do the same to Cinderace.
I’m going to jump ahead to Rotom here. I think that Heliolisk will be better for your team, it benefits from rain as well, will outspeed dragapult with scarf, and is a much safer U-turn option than Dragapult as your physical life orb set will do half to a Dynamax Ludicolo. Run surf on Politoed for more Recovery.
Heliolisk @ Choice Scarf
Ability: Dry Skin
Level: 50
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
- Thunder
- U-turn
- Dark Pulse
- Weather Ball
Next, Dragapult. My favorite Dragapult Tech is Ally Switch. It’s hilariously good against Porygon-Z, which is a quite common team.
I’d also suggest using special Dragapult as Physical Pult almost always wants to Max and you have other Dynamax candidates on your team. Additionally, it gets thunder.
Skipping again to Corviknight. I feel like your team needs another Dynamax Pokémon, as you don’t want to Max Politoed or Heliolisk, and you don’t have to Max Dragapult. Cinderace is a great option as it works great alongside Dragapult as the P-Z buster and is just one of the best sweepers in the game. Against Clefairy + P-Z, Ally Switch and Max Steelspike Clefairy, then Max Knuckle Porygon.
Cinderace @ Assault Vest
Ability: Libero
Level: 50
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Iron Head
- High Jump Kick
- Sucker Punch
- Bounce
Standard set. Assault Vest can throw lots of calculations off and, well... Dragapult already has life orb. Cinderace replaces Corviknight as the Steel/Flying.
Finally, Arcanine. Incineroar is almost definitely better, as it has fake out, parting shot, and non-fire stab, which is better in a rain team.
Incineroar @ Aguav Berry
Ability: Intimidate
Level: 50
EVs: 244 HP / 20 Atk / 84 Def / 148 SpD / 12 Spe
Careful Nature
- Fake Out
- Parting Shot
- Snarl
- Darkest Lariat
You can replace Snarl/Parting Shot with Wil-O-Wisp if you want.
PokePaste
I hope I didn’t change too much and that my suggestions help!