Hello. My dad works for Nintendo. Saying that has become so overdone that it's a cliche, and no one would use it in a fake. That's how you know this is real.
First, Palutena is in. Because she's leaked, duh.
Next, Pac Man and Mii are in, as seen in the other 100% legit leak
Next, Prince Sable is playable. You know this is true, because it's a weird choice and Sakurai likes weird choices.
Now, I've seen art of Rildey, and I don't know the context. Some may say this is me being deliberatly vague so 1/2 of the board won't call me a fake because he's "confirmed playable" or "confirmed stage hazard." But it's true.
I'm not even going to touch DK or Fire Emblem for the same reason. Because I don't know, I mean.
Oh, and Chibi Robo is an assist trophy. It's not a legit leak if you don't disappoint the fans of one character. And Chibi wasn't that likely to begin with anyway, which makes this all the more likely.
Oh, Snake is cut. I know, disappointing. But Kojima said he isn't in, which makes this all the more believable.