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Upon closer inspection, all of the tests aren't conclusive really.
>Fighting
The conclusion here is that Sylveon was unable to defend herself. It could mean she has low physical stats. The steel drum could also represent the move Block, which affects nearly anything. Of course, a Fighting type without good physical stats would be silly, so this conclusion is sound. Until Game Freak trolls us and actually makes it a Special attack focused Fighting type. At this point I wouldn't doubt it.
>Ice
This probably is the most doubtful, since Pokemon learn moves of a dissimilar type. Sylveon breaking the block of ice could very well just be Rock Smash, or hell, Iron Tail.
>Poison
Pic related. That's "Super-Effective?!" in japanese. They just had to put a question mark there to cast a shadow of doubt and create even more confusion.
So the only "facts" we're sure of is that Sylveon is affected by Poison, ruling out Steel, and probably not Fighting.
Oh, and >inb4 anti-fairyfag.
I'm not averse to a new type, I'm just overanalyzing a kid's show like the rest of you.