So, lets start from the beginning, what I would of done was this (this is a example of clicking a button to randomize it, but it could be anything):
Create a new global variable and have it be a number.
Button On Clicked, System -> Set Value -> (Your global variable) -> "round(random(1,3))" ( remove quotes when typing). This is setting the global variable to be a random number between 1 and 3.
Now for another event: Click on your character -> Set Animation -> (Your Global Variable name here without those quotes).
BTW, if you want I can make an example CAPX