Yes, but Sylveon is already a Fairy-type and can learn Fairy-type moves. So, I think its Pixilate HA doesn't utilize its moves (I know that Pixilate STAB Hyper Beam is by far the strongest move of its type) in a unique manner (Except for Mega Pinsir, which gains the Flying-type and gets STAB for its "previously Normal-type" moves upon Mega Evolving). For appearance purposes, Sylveon is the cutest. As for combat purposes, Sylveon is strongest in Special Defense, whereas Leafeon is strongest in Defense. As Jacksepticeye says, "SPEEEEEED IS KEEEEEEEEY!".