..we weren't paying attention. Simple as that. We were all hyped and angry over loosing to Alice, and in the hype we didn't notice Cranidos gain the levels to evolve. By then, it was too late to stop it.
It's a process that, in theory, can be repeated again with Vibrava. The key is forgetting about her. We need to:
1) Grind Vibrava so she is ALMOST at a level (like we are now). Then
2)Immediately swap Vibrava to the back of the party.
3)Challenge Alice a couple times over till we forget about it (Vibrava usually dies to whatever mon it goes out against, so it probably won't level- if it does, then we can always go back to step one).
4) Go back to 'Grinding', and get a switch in on Vibrava for the kill IMMEDIATELY.
In the Alice Hype we will inevitably forget about Vibrava for a while, especially immediately afterwards. Leaving Vibrava in the front isn't an option, as it's too obvious (and doesn't always die like Skull did). Our best option is to get it close to a level, then stuff it away to be forgotten, and then get the lucky switch in.
Edit: Note that this is just an 'in theory' plan that's just a suggestion.
I would put up a more solid plan (pictures and pretty text and all!) if it wasn't for the fact that there isn't a viable way to spread these plans without them being seen by "trolls" (I wish there was a better word for that that wasn't as negative). I've made a post on the issue here, but there weren't any viable answers.