It’s kinda funny that Konami and Capcom have the most characters in Smash and not Sega.
Capcom makes sense though. Capcom has alot of history with Nintendo even without Megaman and Street Fighter. You have:
-the huge number of Capcom Beat-em Ups like Final Fight, Captain Commando, Magic Sword, etc that appeared on the SNES,
-you have Ghosts'n Goblins which is notorious for being one of the hardest NES games in general,
-you have the Phoenix Wright series which every game of the series is on Nintendo handhelds,
-a good number of Capcom series started on Nintendo systems like Bionic Commando and Breath of Fire
-you have the frickin' awesome Capcom developed Disney games like Duck Tales, Chip & Dale Rescue Rangers, Aladdin, etc.
-Monster Hunter got it's rise in popularity in the West after Monster Hunter 3 & 4, both of which came out on Nintendo systems. And I'm aware Monster Hunter World was where it hit gigantic, but before 3 & 4, Monster hunter was niche in the West. Only until after 3 & 4 did Monster Hunter start to become big in the West.
-Resident Evil 4 being exclusive to Gamecube
for a time.
Capcom having a good number of characters in Smash is no surprise, cause when you look at Capcom's history with Nintendo, they have a whole lot.