I say just ignore that guy, Mr. Choco. He just got very lucky, really, in my opinion.
Could be lucky....but he did follow it up by directly saying that whenever they decide to show the direct, it will show Isabelle. Not "probably"; not "might"; not even "highly likely". He flat out said "they will show Isabelle". This last direct just had one small smash part and it was the introduction of just Isabelle.
Dante still seems wildly unlikely to me, but there's two possibilities with this leak:
1) He has insider info and knows with 100% certainty who we've got left (which would be Dante, Incineroar, and Ken) while Skully & Geno are out cold
2) He saw the direct after it was supposed to air on the 7th, knew Isabelle would be in since he saw it, and devised a leak around it while encouraging people to 'screencap' his post so that he'd look more legitimate and it'd be difficult to dispute.
In all honesty, I find #2 more likely, but #1 is not
entirely impossible.
I've said earlier in this thread (probably like 600 pages ago now), but the most heavily disliked leaks tend to be true. At this moment, one of the things that people would dislike the most would be to find out that Skull Kid and Geno both missed their chance in Smash again.
EDIT: Ah, ok. Proof from the director that Dante's not in; hard to dispute that. Alright, that settles it. #2 is probably what happened then.