In this version of Pokemon, I think a Mongoose would fit well with the overall Hawaiian/Californian theme of Pokemon. But at this point, I dont' think Game Freak should make any more new ones. I love them to death but they seem to get weirder looking and weirder looking each generation. Minun is cute however, it's red counterpart, Plusle looks like Minun got it's ears and hands cut off and the blood spewing out of them froze into another pair of arms and ears. Still cute as heck though. Pachirisu is straight up as cute as Minun, Emolga looks weird yet adorable, and Dedenne is straight up weird and unappealing to me. Back to the mongoose. Why Mongoose? The Hawaiian Mongoose. That's about the only rodent that I can think of that fits with the Hawaiian theme. Hopefully the mongoose would look adorable. Maybe it might be a little taller than your average "Pikaclone". If we can still fit in the style of the pre-Dedenne ones, I think it's best to give one of them an evolution. Preferably Pachirisu.
As for m personal preferences, a racoon would be amazing. A mini Riolu with a cute face like Minun. I think I would fall in love with it if it doesn't look out of place.
Also, guys... The "Pikaclones" do not look as much like Pikachu at all. Just their cute little faces are similar to a Pikachu.(I think Pikafaces look better on them than Pikachu itself.) Most of them are more rounder looking than Pikachu and have completely different body shapes than it. Plus, they are all different animals and even they all have higher base stats than Pikachu. I get really annoyed when people compare them to Pikachu like they're blatent ripoffs.