» those thousand words ♥
This is just my own personal advice, but take it with a grain of salt until a more experienced regular(like Karpman or Vrai or someone else) answers your inquiry, too.
As Vrai has stated, Alakazam has a fairly high base speed, and although it's pretty frail, it's offenses(well, special attack) isn't really anything to scoff at. As far as Espeon is concerned, Magic Bounce allows it to set up Reflect/Light Screen(without any fear from Taunt and it also wards away entry hazards) and also, due to it's ability, it makes quite an impressive Baton Pass user.
Remember that Espeon doesn't have excellent defenses either, but also understand that the defenses aren't really the purpose of these Pokemon. Alakazam need not worry about defenses a lot of the time if used correctly(I believe it can set up a CM or two before sweeping? Correct me if I'm wrong here). But again, it depends on what would be more beneficial to your team. n___n;