I've been trying for days to change the gender of my pet Tijuana (who will also need to be an experiment), but I can't seem to get his gender to change! Am I just unlucky or is it infrequent now?

Now that you mention it, I don't recall getting a gender change on any of the pets I've zapped recently. But luckily the isn't very expensive

I know about the sex berry but I'd rather not spend sP on it, haha. thanks though!

Well, yeah there's that but I honestly am not sure the zapper is changing genders currently. I've been zapping consistently since February and I don't recall any gender changes (and none of my pets ended up as the wrong gender once I got their zaps, since I haven't used a Sex Berry)