I always participate in tournaments but i always get either 13pts-17pts, my biggest was a one time 20pts. i thought if you have more pillz left higher the battle points, but that was in correct, i got my 20 pts with zero pillz.
You got your 20 points because you won by Knock Out.
In tournaments, there is currently no good way to get A LOT of points.
But, in normal mode, you can just play without pillz and get your KO pillz bonus, probably 45 -