Well, a good thing to think is which addition they should incorporate in each game to avoid being a strait port(please not amiibo). If the added content is enough, the game could still feel like a new one.
I'd happy with a 10 newcomers and a switch mode in smash. A port would feel like a new game.
Add DCKR stages to DKCTF. Playing the old ones with Dixie and cranky could add different possibilities.
Botw content to hyrule warriors. Playing as link(imagine the weapon possibility) urbosa, daruk, revali, minha, Sidon, Zelda, a guardian, lynel , yiga, and include a new story line, wow. Or just call it hyrule champions.
Add 2 player play to Mario maker. And slopes.
Yoshi ww, hmm, add Kirby epic yarn to the package.Add cap. Toad to 3d world, pikmin 1 and 2 to pikmin 3, add four swords adventures (sharing joycon) to tphd and wwhd, and sell as Zelda GameCube collection. Nsmb 1,2, wii/u+luigi, 4 player and nabbitt invasion for stages of the other games too.