Nintendo has given us a heads-up on where the next character is coming from.
Earlier this year, Byleth from Fire Emblem: Three Houses was announced as the final character in the first wave of new challengers. The second Fighter's Pass includes six characters and we now know when to expect the first one. Today, during a Nintendo Direct mini showcase, Nintendo shared the news that the next Super Smash Bros. Ultimate character will come from the fighting game Arms.
This is a companion discussion topic for the original entry at https://www.imore.com/next-super-smash-bros-ultimate-fighter-arms-character-reveal-and-release-date-coming-june