As for the new characters and my thoughts on them; well in the case of Animal Crossing, I felt they deserved a representative, as they had everything but a character in brawl. I'm disappointed to see that it's not Tom Nook but simply undefined protagonist, but he does play how I imagined an Animal Crossing representative would and I love how the fandom has reacted to him.
Mega man had me worried for a second but thankfully it's already been mentioned that third party characters will be kept to a minimum; http://www.nintendolife.com/news/2013/06/third_party_characters_in_smash_bros_to_be_kept_to_a_minimum. With that being confirmed I have nothing but love for this choice, he deserves a spot in SSB, and I find his playstyle interesting.
Finally there is Wii Fit Trainer. Sakurai wanted a character that no one expected, and well... we certainly didn't expect that. It's questionable when you mention it but the video showed her off well and she looks to have a well-made move-set and fighting style. It's also nice to see a new female character, and while there are plenty of other female characters that could have been chosen, it's nice to see a female character that represents a new series.
As for characters I want to see appear, I personally think (and would to see) that Ridley and Little Mac are long overdue a playable role. It was nice to see them included in Brawl but I want them playable and think they deserve it. My most wanted character though would be Lip from Panel de Pon (Puzzle League), but while there are quite a few reasons she?d be good for the game?s line up I don?t think her chances are all that high. Still, one can dream.
Other characters I?d love to see as playable characters include Shy Guy (unlikely but another Yoshi representative would be great), Ashley, Tingle, Starfy, Samurai Goroh and Medusa. I don?t think the Kirby series needs another representative but I won?t complain if another one is in, it is my favourite series after all, and I would love see N, or at least a Black/white/X/Y trainer replace the current Pokémon trainer. I would say Grovyle from Pokémon Mystery Dungeons series but I highly doubt he will appear (a stage however would be likely and epic).