>Characters who became popular recently
Roy and Greninja were developed into smash before their games were even released. I don't think being characters from modern games discredits them. Also Shantae's modern popularity has been on the map longer than Shulk(Well, Internationally at least), Robin, Lucina, Greninja, and the modern popularity of the Kid Icarus characters. She was rebooted early 2011, they all followed suit later.

Title, While I get where you're coming from with Shovel Knight, and while you've already been called for some things, and while I'm also hoping for K. Rool, Krystal, Snake, and Segata Sanshiro, I have to correct you one small detail. Shantae's first game was on Gameboy Color, her second on DSiWare, and her third on 3DS, in other words, she's had more than enough time to become a classic.