>>12048745Fine. Look at this image. Note that all Eeveelutions face a type they're weak/strong against. Sylveon faces Jolteon.
Sylveon is the lightest of all Eeveelutions. If going on the upper theory that they all face something they're strong or weak against, it doesn't make sense that a ground-type would be light. Thus, leaving us with Flying.
Sylveons name is based off Sylph (English name) and Nymph (French and japanese name) both are fairies with wings, flying around in the air. Obviously a Pokémon based on these would be flying
Dont't start shit about fairy typeFinally, note in the gameplay video that its ribbons flow around, looking like they're in the wind. Wind is obviously related to flying types.