Espeon with Future Sight is a supreme counter for Machamp; the same for Alakazam. But Dazzling Gleam deals 2 x 100 damage to the 120 of Future Sight and is also effective against Fighters. This would suggest that Dazzling Gleam is better on Alakazam, as even without STAB it deals more damage.
The same line of thinking suggests Clefable as a supreme Machamp counter. Here Dazzling Gleam has STAB. This makes up for the lower ATK stat of Clefable, leaving you with an attacker that is both stronger and tankier than Espeon.
So... why does this not work?
It works, my DPS source list Ala DG as 6th:
Alakazam Confusion Futuresight 146.33%
Alakazam Psycho Cut Futuresight 142.08%
Espeon Confusion Futuresight 141.21%
Espeon Zen Headbutt Futuresight 137.93%
Alakazam Confusion Psychic 136.12%
Alakazam Confusion Dazzling Gleam 133.85%
Clefa has way to low attack probably:
Clefable Zen Headbutt Dazzling Gleam 88.41%
