I think I'm pretty late to reply already and I didn't do it on intense but my strat was Nancy's sylveon (max evs on special atk and special def), she couldn't kill sylveon in 2 hits so I did moonblast, moonblast, ultra potion, btw you gotta wish on every moonblast that sylveon wakes up XD, but yah, I was able to go through her (normal diff again), with just sylveon