Espeon-GX is not really looked at unlike Taurus-GX, Lurantis-GX, and the Sun/Moon-GXs. However, it could be grandly useable. It has Psychic, which is [PCC] for 60+, and 30+ for each Energy on their active. Against MMewtwo, it can easily one-shot, giving it a good Mewtwo matchup. Against Volcanion, it can do about 150 of they have 3, which normally is the maximum amount of energy on a volcanion card. This gives it a good matchup say if you play Espeon with Garbodor, so they have no Abilities, and you have 200 HP, so you can take a couple of hits. Mega Scizor is a bad matchup by far, with your maximum damage output being 100. Not very strong. Not at all. Lurantis GX is a nice matchup, because they might end up stacking up some energy to use Chloro-Blade. There are many more decks that this deck can hit but I just wanted to trigger discussion.
(PS: Bad MGarde Magchup)
(PS: Bad MGarde Magchup)