I like young link more idk I feel he represents the young link demographic better, he would be decloned of course, gene sect is a flavor of the month Pokemon, until he is a dominate favorite in the series and across poke fans I probly won't add him, chrom is a flavor of the month fe character (although I bet he will be included due to the stage) if he earns his spot in multiple fe games or holds an important spot in fe history then id add him, until then he is just a popular random. Demise I believe to be important as he is the original source of the dark power, impa is a very consistent character in the universe her role is linked into the history repeating sort of thing and she could replace shiek well, and for Tom nook he is more iconic than villager is to the animal crossing series and I wouldn't be surprised to see him in ssb4, not including Ac also has 4 enties.