Are you saying you doubt that the developers of one of the most complex & successful fighting game franchises in the industry wouldn’t know how to balance guest fighters when they already successfully did so in T7?
Especially when they regularly do so for Soul Calibur which has had a long history of guest fighters?
The same devs who also collaborated on SSB4 & SSBU, titles whose guest characters played vastly different from other characters on the roster?
"With such an impressive catalog, players would potentially be able to unlock and then play against each other as characters as famously overpowered as Goku from Dragon Ball to see who is truly the strongest."
Did you even play Tekken 7? You can have a regular guy with a bat like Negan defeat the likes of Kazuya, Heihachi, Jin & Akuma.
Did you even play any crossover game where Dragon Ball is present? Goku isn’t always the best character gameplay wise in every game he’s in. Neither is Superman.
Just because a character is extremely weak or strong in their source material, especially compared to another series, doesn’t mean they can’t be balanced in a crossover fighting game, or any genre for that matter. There’s so many countless examples of this basic game design principle that it’d be embarrassing to even have to name any other examples of such an obvious occurrence.
Just in case you still don’t understand how much of a nonissue this really is, here’s a link further showing how common it’s handled
Hell even Tekken original characters are designed to be able to be viable against the entire Tekken series roster no matter how powerful they are in the lore, so don’t give me that BS
"Are you saying you doubt that the developers of one of the most complex & successful fighting game franchises in the industry wouldn’t know how to balance guest fighters when they already successfully did so in T7?"
That's a weird statement given that Akuma&Geese had the worst balance in ages with their mechanics and disgruntled the entire playerbase by winning high-profile tournaments en Masse.
You can say a lot about Tekken 7, but the balance is one of the main weaknesses and called out regularly by veterans&pros of the game.
I'm sorry but smash bros has some of the most basic movements compared to tekken. The balancing would be a nightmare for devs
The only other fighting game series aside from Super Smash Bros with a recurring guest character was Dead or Alive with Mai Shiranui
With Tekken I can only see Akuma legitimately returning since he’s now part of Tekken’s established lore.