I know that some winners used Fake Out, which is 40 BP, but I was wondering if someone won Worlds with a mon knowing a move with less base power?
Disregarding all the 0-power status moves, and variable-power moves like Gyro Ball which are coded with 1 power and have a special routine to overwrite that upon use...
Wolfe Glick's 2016 champion team had a Raichu with Nuzzle, which is 20 power. The only moves that can possibly go lower than that are temporary trapping moves (Wrap), multi-hit moves (Water Shuriken), Constrict, and Poison Sting, but none of these teams used any of those moves.