It's one of those things where there's so many different pets out there that "non-popular" could be hundreds of pets.
I love the theory rafting in trying to get some synergy out of these teams, but that 3rd spot becomes hard to fill.
Plus, when you can sort by "spell I want" on This site and find a 3rd that's rarely used but not on the list, well, that's the request I'd make too.
Although alternately if we did this again you could always prohibit the 150 most popular or something.
Really it's too bad there isn't data on team popularity... I'd love to see what % of teams run anub, etc.