Krysco
Aeon Hero
If Radiant Dawn was actually advertised and advertised well then Micaiah may have had a likely shot of being in Smash. Her significance to the series isn't too much (though I believe she's the first 'lord' to be a mage? Could be wrong on that.) but then the same applies to Robin and Lucina. Robin was added in over Chrom simply because he could be original while Lucina was just a skin/clone and took little work. Marth was the beginning of it all and Ike is the only other lord to get 2 games and is also the first one to appear 3D outside of Smash. As for Roy...he was just an advertisement and then brought back because of his fan base...
*Waits an eternity for Wolf to get the same treatment*
*Waits an eternity for Wolf to get the same treatment*