Champions Archetype · Regulation M-C
Rain
Pelipper Drizzle + Basculegion Swift Swim. 2x Water + halved Fire wins half its games by turn 3.
The build
Rain remains a ladder staple. Drizzle Pelipper sets the field; Basculegion (Adaptability + Wave Crash) and Archaludon clean up. Rain also doubles Thunder accuracy to 100% which is the secondary win condition.
Signature Pokémon
Pelipper 
Basculegion 
Archaludon 
Gyarados Lead options
Pelipper + Basculegion is the classic. Pelipper + Archaludon for special-attacker variant.
Win condition
Drizzle up turn 1, Wave Crash / Hydro Pump / Thunder before your 8 turns of Rain run out.
Hard counters
Sun (Charizard) flips it. Grass-types resist Water. Goodra / Empoleon / Toxapex tank rain hits and stall.
Signature moves
Sample team
Plug-and-play 6-Pokémon roster you can import to the team builder. Adjust EVs / nature / move slots based on your specific local meta and tournament reg.
Incineroar 
Whimsicott 
Garchomp