I mean, I don't want to be "that guy," but if I was building an eevee deck, Leafeon would be the first thing I put in, I'm not sure why you didn't have it in the first place. (Unless your meta is extremely Pyroar heavy or something.) The most success I've seen from an eevee deck was pretty much just straight Eevees and Deoxys, no thundurus or lugia or anything. I would run 2 Leafeon, 2 Flareon, a Glaceon (gives Deoxys free retreat), and 1 or2 Espeon. Maybe a Vaporeon to counter Landorus, but tbh, since all of your guys are plasma anyways, you could probably get away with running Plasma Kyurem as well.
One of the guys in my league put an interesting spin on it though - he played it with 2 Leafeon, 2 Flareon, a Glaceon, and an Espeon, but he also included Pyroar. He played extra fire energy so he was able to Blacksmith. It's a lot to put into a deck, but it helps a lot against anything that isn't Seismitoad/Garbodor. Aside from the Pyroar, it was pretty standard. He also played Training Center + Mr. Mime, so Landorus had a very hard time against the deck. It was unable to set up quick KOs, and usually you'd end up overwhelming it with Leafeon and Flareon.