Pretty sure Sylveon is the best Eevee cleric if you go that route. That Eevee is viable in ubers of all places as a cleric.
Stat wise, Umbreon is still a better choice. They tie for HP and SDef, but Umbreons 110 Def destroys Sylvie's 65.
It can hold the cleric role well, and has the overall stats to tank. It really comes down to what the player wants.
Sylveon has better typing with uncommon weaknesses and a powerful attack in Hyper Voice. Better than lol Foul Play.
Yeah Umbreon's higher Def doesn't amount to much when it is weak to Close Combat and U-turn, two of the most important attacks in the game. While Sylveon isn't as strong for physical defense, pixilate Hyper Voice rivals Jolteon and Glaceon for STAB damage while having the added bonus of piercing subs and hitting both opponents in doubles. Given how saturated ubers is with dragons, Sylveon is more valuable in the tier than any other Eevee.
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