When throwing a item to a mob, the mob should disappear.

Hi folks,

I'm currently making a new mod for 1.18.2, which is similar to Pixelmon. It adds all the new Pokemon from the 9th generation into the game. Now I want to do the mechanic to catch the Pokemon and I thought about the following procedure: When the player is dropping or throwing the ball, the Pokemon should disappear with a 30% chance and it should be catched with a 70% chance, exactly reversed at the two boss Pokemon Koraidon and Miraidon. But I don't know how I can do this in a procedure. Can someone help me pls?

Sincerely yours,

Atten007