Short answers, pulled from the story.
The Variable Assist is a mechanic that lets a player summon their off-screen teammate to perform a special move without swapping out the active fighter. It expanded combo options and became the foundation for assist systems in later Marvel vs. Capcom games.
Norimaro is an original character created by Japanese comedian Noritake Kinashi, exclusive to the Japanese version of the game. Marvel refused international licensing because Norimaro did not fit their brand image. He became playable outside Japan when the Marvel vs. Capcom Fighting Collection: Arcade Classics was released in September 2024.
The Sega Saturn version of Marvel Super Heroes vs. Street Fighter was released on the 22nd of October 1998, exclusively in Japan. It used the 4MB RAM expansion cartridge and was considered an arcade-perfect conversion by reviewers.
The PlayStation version removed tag team play because the console's RAM could not support the format. Capcom replaced it with a round-based system and added exclusive modes including Hero Battle and Cross Over to compensate.
Marvel Super Heroes vs. Street Fighter has 17 playable characters: nine from Street Fighter and eight from Marvel. The Marvel roster includes Captain America, Spider-Man, the Hulk, Cyclops, and Wolverine. The game also includes six secret characters, all palette swaps of existing fighters with different movesets.
The sequel is Marvel vs. Capcom: Clash of Super Heroes, released in arcades in Japan and North America in 1998. It expanded the Capcom roster beyond Street Fighter to include characters from Darkstalkers and Mega Man, and replaced the Variable Assist with a new system.