FB 125% effective 0% IV: 68 DPS
FS 125% effective 0% IV: 75.556 DPS
DPS for charged moves is irrelevant. To really compare, "time-corrected EPS" or weave damage with a fast attack is neccesairy.
Fighting and Poison Pokémon are usually toothless on gym defense because of the base STA, excluding Muk and Machamp.
Thus, finding a pokémon that Future Sight is super effective against is hard, while Focus Blast (without STAB) being very easy because of those Blisseys and Snorlaxes.
True - Type Psychic is largely unresistet, and largely not super effective. So it is somehow reasonable to compare SE-Fighting moves with STAB Psychic moves.
Unless your Alakazam really has 0% STA IV and a low level, I would say Focus Blast is better because of the 0.8 multiplier of Zen Headbutt.
Either i have a black out, or this is pure none-sense. I do not feel like having a black out.
The 0.7 seconds won't affect that much when using the charge move just after the defender attacks.
If you refere to different cooldown of charged moves, they matter threefold:
(1) Time, you cannot dodge
(2) Time, your fast attack does not generate energy
(3) Time, your fast attack does not deal damage.
0,7 seconds is not small in respect to all of those points.