It's Smash, it doesn't need to be 100% logical and accurate.
Otherwise, Jigglypuff grabbing on to people just by poking them would not be. Pretty sure a Jigglypuff can't actually grab another character due to its stubby, fingerless arms/hands, with the only excuse being "Kirby does it". In fact, a hefty sum of Jigglypuff's attacks were taken from Kirby.
And like I said, early moveset. At this point, I would take B/W into account and also have Eevee latch onto the opponent to grab them.
You also talk as if being limited in physical capability is a bad thing. That since Sylveon has those ribbon things, it will magically have more to work with.
NEWSFLASH: All that means that instead of tail attacks, Sylveon will be limited to using the ribbons for the exact same purpose. And instead of "psychic projectiles", it has to resort to "magic projectiles", which in the context of Smash, is barely different.
So what have we learned?
Eevee and all its evolutions are all just as capable to grab and attack, though how they would depends on the 'Eon. And all are just as limited in what they can do as the others.
Sylveon is not a special case in any regard.
But what if it's actually a Punch Out!! stage, but its like Smashville in Brawl? (A stage that doesn't have a character to go with it.)
