The other two pretty much explained it, but they didn't mention that simply opening Fright Night isn't necessarily going to happen 100% of the time. Also, is you prize any, you're screwed. And a good Gardevoir player can get around Yveltal ridiculously easily, so I would suggest playing 3 Fright Night. If you play 4 big birds, I would like to point out the only matchup you need 4 for is Greninja, so if you want to beat Gardevoir (not to mention other matchups) you should suggest the 3-3 split. You could also tech Darkrai-EX (or the cringe-worthy Umbreon-EX) since they both resist Garde, and slam for decent damage. You also don't want to set up Garb until they mega evolve at least 1 Gardevoir-EX. Some of my friends also play both Olympia as well as Pokémon Center Lady, since healing is so good in this meta.