Question: what is the best level to evolve eevee into sylveon?
Answer: If you are catching eevee in the wild, best lvl to evolve is 20 because Sylveon learns Draining Kiss, a 50 power fairy draining move at 20, and it is really tanky with that move at that lvl. Still best time to do it, in terms of picking up the best move for it. Any time before level 20.