IMHO, Goroh's chance was based primarily on the fact that there weren't many other F-Zero racers to choose from. This, of course, is quite unrelated to Geno, who isn't related to F-Zero in anyway. The same could be said for Deoxys, really (because when you really boil things down, there aren't THAT many pokemon with a decent chance of being playable out there). Needless to say, Geno's situation is a different thing from those two altogether and his chances generally shouldn't be gauged based on those two not getting in.
Of course, even Sakurai starts off the Deoxys post with "This one is popular!"
A lot of Geno's 'chances' are all based on wild cards. How much of a third party character does he count as? Does he count as a Mario character or not? Does Sakurai even care or mind if Mario gets 'overrepped'? How much does popularity count for (because even Sakurai states in the latest post that Deoxys is popular and yet Deoxys is not playable)? How much does Square or Nintendo even actually remember him? Just how does Sakurai or maybe Miyamoto feel themselves about these things? Do they even CARE? Yadayadayada. Most of these are all speculations of which there's no way to know the answers to the questions. There aren't any precedents for those criteria in any past Smash game (except maybe popularity, but even that isn't certain).
All you can do is look at the criteria that you think Geno fits and hope or pray that's enough to get him in (...or out, in some peoples' cases, like mine!
)
Assist Trophies are another beast altogether.
