Well, I think we need to categorise further. There is a pretty significant difference between thinking a character COULDN'T be in the game and thinking on SHOULDN'T. I suppose without personal opinion this forum site and pretty much everything in the world would be bland. But I think that alot of the split decision characters could be put more into the SHOULDN'T and COULDN'T categories. I'll give it a shot. Note that I am putting them into negatives moreso than positives. As in why people dont want a character in.
SHOULDN'T
Krystal - most people just dont like the people who support her, and figure she isn't big enough of a character. She COULD be in because she is a female and has a staff, which is unique.
Geno - Again most people think that he hasn't had a big enough history to make the roster. I had no idea who he was when I first started reading here.
Bowser Jr. - I figure most people against Bowser Jr just think he is annoying. I never would have thought him to be a good enough character for Brawl, but he has been a main villain and starred alongside Bowser for a while now.
Marth - The only people that doubt Marth are the Roy users. That's fair enough since most of the people who doubt Roy are Marth users. This one is purely personal.
Isaac - I'll tread carefully cause I like Isaac. Most don't know him. He has a cult following in Europe mainly but not too big a following elsewhere. He has an awesome moveset potential and easily fits in, but most feel that he isn't popular enough.
Mewtwo - I didn't realise that he was doubted, but i think it's mainly due to his not so greatness in Melee. For the ultimate pokemon, he was a pretty lackluster character. He could easily be spruced up, made cooler. But most will always remember his poor entrance into the smash community.
WW Link - Purely shouldn't arguments for WW Link. That would be a clone, that one link is enough. There is no real argument as to why he actually couldn't be a character.
AC - Due to the peacefl nature of the Animal Crossers in general, an AC character has been doubted.
COULDN'T
Ridley - Most prominent argument is his size. People would love for him to be in, but doubt it because they say he is too big to be playable.
Ness - Lucas, pure and simple. Due to Lucas, Ness couldn;t be in brawl. The clear cut argument.
Lucario - Whilst he is a cool fighting pokemon, partially thought of as legendary, most people believe he couldn't be in brawl because we would have too many pokemon characters. That would be the main argument.
Yeah, that's my take on it. I hope you all get where I am heading with it. Oh, and I never really doubted Jigglypuff and thought most people didnt either. So I haven't put it in.
Keep in mind, that these are my personal takes on each character, as in, what I think is the main reason for doubts.
