On January 21st, the official Japanese twitter account for Super Smash Bros. announced an upcoming Spirit Board event based on the Kunio-Kun franchise.
According to a translation provided by Smashboards writer Venus of the Desert Bloom, the tweet reads "Characters from the series 'Hot Blooded Kunikun' hits the spirits board! For five days, starting from 1/24 (Fri), the event 'Hot-Blooded Smash Bros Downtown March' will be held. Please check out the 4 new spirits!"
The name of the event is in reference to Downtown - Nekketsu Monogatari, the original Japanese title for River City Ransom, one of the most iconic games in the Kunio-Kun franchise. It was confirmed in a later tweet that the Spirit on the left is Kunio, also known as Alex in some Western releases, the main protagonist of River City Ransom. A later tweet confirmed that the two characters on the top right are Ryuuji and Ryuichi, also known as Andy and Randy. They serve as the main villains for much of River City Ransom, and are both fought at the same time in a boss battle inspired by Double Dragon, complete with that game's title theme as their boss music.
As for the other two characters, the one in the middle is most likely Riki, also known as Ryan in the North American release of River City Ransom. He is the secondary protagonist of most of the Kunio-Kun games, and is usually controlled by the second player. On the bottom is what seems to be Goda, named Ivan in most localized versions. He's another late game boss that appears leading up to the encounter with Ryuuji and Ryuichi.
At the time of writing, there is no information as to whether this Spirit Board event will be available in other regions, and if so, whether the original names and sprites will be used in Western territories, or if the names and sprites from the North American release of River City Ransom will be used instead.