Here is the full list of all 23 Lethal League achievements.
Reach a ball speed of one million
Hit three players in a row
Play a hundred matches
Rally the ball back and forth for at least ten times
Reach level 20
Reach a ball speed of a hundred thousand
Bunt the ball at 1000 speed or above
Get hit by your own ball
Beat the challenge mode with Switch
Reach level 10
Hit two players in a row
Reach a ball speed of one thousand
Reach a ball speed of two hundred fifty
Reach a ball speed of one hundred
Play five hundred matches
Play one thousand matches
Beat the challenge mode with Raptor
Beat challenge mode with Candyman
Beat the challenge mode with Sonata
Beat the challenge mode with Latch
Beat the challenge mode without using any continues
Beat the challenge mode with every character
Beat the challenge mode with Dice