I think kicking the vending machine lowers intelligence? o:
... I had no idea about that. But oh boy, it looks like the pet it hits and whether it increases or decreases is completely random. >_>;;; Oof, that would be a whole other can of worms.
Oh, man. I have that exact same fear with one of my pets, too-- if their level to go above 20 or any of their STR/DEF/HP to go above 99, then I'm gonna be extremely upset. :'|
It's weird that there's no way to decrease level or intelligence right now, though, just the other four stats... you could just get down to kicking that vending machine 24/7, but the randomness sucks.
I am so glad that I learned to not care about that. Used to have most of my Pets at 100 in all stats but Scratchcards and other things ruined my life.