There used to be a glitch where you could create pets with -1 stats if you hit "stop" on your browser right as they were being created. IDK if it affected level or not, but their weight and height was set to 0 too I believe?
Stat decreasers (both as random events and as items, presumably) exist just as increasers do, so it doesn't seem too farfetch'd.
Do it for the aesthetic or something.