I stand corrected.
That said given what DK has been through (Everything between country 3 and Returns was pretty much balls, barr Mario Vs. Donkey Kong which is different, and hardly a DK game by smash standards) it too is growing, at least back to it's older popularity, since Retro got a hold of it.
Kirby is also worth noting is basically the testing ground of Nintendo, his games tend to sell poorly due to the significant differences between them as HAL try out new game design ideas... it's risky, and few people can be bothered to keep up.. heck, a platformer where you can fly infinitely is already a bit of an experiment back in the first dreamland games, so I think he's more important to Nintendo than the sales figures alone.
I also said in my post I don't think Star Fox deserves 3 characters, but they're there, the space animals are a huge part of smash, and they shouldn't be removed.
Metroid, or more precisely, Ridley-wise it's all about fan appeasing, and they're a vocal bunch...
Back to AC:
Maybe it deserves a second rep then, but even then I think the Girl Villager would be a better choice for more AC work... I mean, Tom Nook's just the guy you buy stuff from, the game is about the player character and the friends you make in the village, and there's certainly not enough slots to fit them all in...
I think if there was actually an obvious choice, and not just a ball-less (ie. just an animal, no mythical powers) tanuki chosen because there should be another an animal crossing rep, I'd be up for it, but there isn't as far as I'm concerned...