SSJBlastoise said:
With the Sylveon typing I originally thought it would be flying from the way it looks (parts floating around it) but from the video revealing it there didn't really appear to be any flying type moves and they all looked like they might be normal type attacks but that's just a guess because I could only recognise swift.
I see Sylveon using moves with strong resemblances to known Eevee staples: Quick Attack, Swift, Last Resort... and a billowing attack that looks suspiciously like Gust or Hurricane. I could be wrong, of course... assuming the visuals look in any way like the previous games' animations when generations tend to change up the imagery.
Below is a theory that popped up a week or two ago about the type of Sylveon (I'm not really a big fan of this theory but it is interesting). It suggests that each eeveelution has a pairing where each pair has one type advantage and the one left over was Jolteon which means Sylveon could be either flying or ground. The flaw I find in this is why did the person that came up with this leave Jolteon last? Why isn't Vaporeon it's pairing? Anyway, it is just a theory that someone has come up with.
There may be some more complexity to this theory, I think. Thus:
Flareon (fire) is strong against Glaceon (ice) and Leafeon (grass), weak against Vaporeon (water): 2-1
Vaporeon (water) is strong against Flareon (fire); weak against Leafeon (grass) and Jolteon (electric): 1-2
Jolteon (electric) is strong against Vaporeon (water)... 1-0
Espeon (psychic) is weak against Umbreon (dark)... 0-1
Umbreon (dark) is strong against Espeon (psychic)... 1-0
Glaceon (ice) is strong against Leafeon (grass); weak against Flareaon (fire): 1-1
Leafeon (grass) is strong against Vaporeon (water); weak against Glaceon (ice) and Flareon (fire): 1-2
Strangely enough, expanding the theory leaves Espeon as odd-eon-out, having no type advantages and one weakness.
Umbreon and Jolteon have no weaknesses and exactly one strength;
Vaporeon and Glaceon have one strength and two weaknesses;
Glaceon is the only one who breaks even, and Flareon is the only -eon with two advantages.
Based purely on this type dis/advantage data:
To balance Sylveon with the other -eons, it must be weak to Ice and Ice alone (among these types) while having no other type advantages (again, among these). This pairs off Glaceon with Flareon at 2-1 and Sylveon with Espeon at 0-1. That means, if I read the chart [http://serebii.net/games/type.shtml] correctly, that Sylveon must be the Dragon type.