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Dang you're majorly screwed up now. As yoshikiller previously mentioned, you only get bad eggs through cheating. And if you're lucky, the egg will just never hatch but you can't get rid of it either. Or, if you're prone to bad luck, the bad egg will keep on hatching after every step you take, and it will hatch into more bad eggs. And if you let it go on it screws your game over so badly that you can't save on your game again and the internal battery runs dry. (Oh, and clock-events don't work either).
Although, this can all easily be prevented by not cheating at all(or if the bad eggs messed you up resetting your game) but of course, it is your choice of whether you want to use a cheating device or not.