https://www.gamespot.com/articles/e3-2018-metroids-ridley-is-a-playable-character-in/1100-6459757/

As if Super Smash Bros. Ultimate's roster of "every character from the series history ever," wasn't enough, Nintendo closed it's E3 2018 presentation with a surprise Smash reveal: long-time Metroid antagonist Ridley is coming to the game.