If memory serves, Pokemon Smash themselves have never made an official reveal. They get people who are actually working on the games (like Masuda) to come on and make reveals.
So while it's possible all this testing Sylveon's type stuff might be some big publicity stunt put together by GameFreak and Pokemon Smash, it's also possible that it's just humorous sketches that they put together based on the fact that we don't know what type Sylveon is.
Don't forget to check out my MegaTen themed webcomics at http://www.drunkduck.com/user/Strain42/ (Currently Updating: Persona 4TW Add-On M-F)
I feel like a lot of people treat Pokemon Smash like it's just a news show, when it's really not. At all.
It does deliver news from time to time, they gave us Newtwo before anything else (ignoring leaks of course) as well as first gameplay footage. Granted it wouldn't be my first choice but to completely ignore it is silly as well.
Sure, it does occasionally have some news, but that's not the point of the show.
Some people go as far as to analyze the hell out of every little thing that happens on the show just to try to find "clues" about the games. I think this is one of those times.
Maybe, maybe not. We don't know, the fact that they were playing with the idea does give some credit to the theory so lets at least give it that. Either way, it's best not to rattle cages and instead wait for this to be addressed next week.