I unfortunately tend to get stuck when considering rarepairs in Love Live, because I always second-guess myself on how rare the pair actually is. Are there guidelines for rarity, or is it just anyone this side of the Established Pairings? Like, I figure NicoMaki, NozoEli, ChikaRiko, and YuuPomu are probably out, but how obscure are you looking for?
Should be a fun tournament, anyway!
if you have to think hard and ask yourself "does this count as a rarepair?", you should consider submitting something else instead.
there are quite a few pairings outside of The Big Ones that are still popular enough to not count as rarepairs in my opinion. ultimately I'll be making the calls, but if people disagree with my initial judgement I'll try to look at evidence such as fanart/fanfic tags on various sites and and reconsider.
I'm glad you're looking forward to it!