This is interesting... heck it even sounds believable! And best of all, Shulk's playstyle sounds exactly how I would've expected Sakurai to handle it. I'm content :3
"his neutral special makes his sword really big" - This sounds like Monado Buster but there isn't a whole lot of information on it... Is there no attack? Does the sword just get bigger? Who knows...
"his down special is basically counter, but it stuns to opponent temporarily" - Well I imagine this is how his visions are going to be implemented. I like this, since it's the obvious choice, but still unique. A short stun opens up a lot and by the sound of it he'll be able to utilise it well.
"His recovery isn't fantastic, but it makes people trip if you hit them from the ground, it also has really good range from the ground." - Monado Cyclone? The trip concept is interesting, since y'know... 'cyclone'. And as we expected, the recovery is mediocre.
"Also, his side smash does a HUGE amount of damage when you hit an opponent from behind. Seriously though, if you counter someone, you can hit them from behind and it HURTS." - No prizes for guessing what move this is. Sounds perfect.
And why do I believe all of this? Well obviously he might be lying, but he said he hasn't played Xenoblade yet. The moves he explains are identifiable to someone who has played it, but not to someone who hasn't.
Also, this: "the ability to talk with Hades and Varidi about characters you're facing."