No guest character has brought in any significant jump in tournaments players ever.
At best you will see established players using guest characters as pocket trolls.
Man you don’t know that all. You have no idea how many casual players picked up a game and started to play, then decided to play seriously because their favorite character was in a game.
I know we have a player way back in the sc2 days that started playing soul calibur 2 on the GameCube strictly because of link.
Dude was really good and only really played link in casuals but had a nasty cass.
Ironically enough he started playing tekken also later on down the line.