Having both used Espeon / Xatu and faced many, many teams with Espeon on the PO server I have some observations that I'd like to share.
First off, Espeon usage drastically decreases as you go up the player rankings list. At the moment I'm in the top 50 (so high 1300s, low 1400s) on the PO server and, to be brutally honest, very few of the high ranked players use Espeon. I'm not sure how to explain it, unfortunately, but I think that it has to do with Espeon, as a pure Psychic type, just not fitting into the sorts of teams you'd see in the upper levels. Your basic sand offense doesn't need it, rain offense doesn't need it, sand defense has better options, other weather types might consider it but they're not really viable (sun is barely viable but often Xatu works better due to the ground immunity). Stall can use it but it doesn't need it and direct offense is out of style thanks to the large amount of revenge killers and Ditto.
Other than the decrease in usage, I'd also like to point out that any Espeon I _do_ see has absolutely no synergy with the team. Like, at all. And I understand that it's very hard to fit a pure Psychic type on a team nowadays but like it's as if people just add in Espeon because they need a 6th Pokemon and just decided "hey I think my team is weak to sr, better use espeon!"
And, on a final note, usually I end up setting my entry hazard(s) anyway so it's really just a matter of outwitting the Espeon until it dies or, and this is more likely, just plowing through it since Psychic is not a good attacking type and Espeon is going to rely on using a few obvious / low power moves.
tl;dr I don't think this Pokemon actually accomplishes much, but that may be because of how it's being used