Here is the full list of all 13 Lethal League trophies - there are 9 bronze, 3 silver and 1 gold.
Reach level 22
Play a hundred matches
Reach level 11
Hit three players in a row
Bunt the ball at 1000 speed or above
Reach a ball speed of one thousand
Rally the ball back and forth for at least ten times
Get hit by your own ball
Reach a ball speed of one million
Reach level 33
Beat the challenge mode
Beat the challenge mode without using any continues
Beat the challenge mode with every character