drcossack:
My own tests show that Feint prevents not only Wide Guard's effect, but also Quick Guard's effect, both when the opponent or its partner used either move. This behavior, for example, enables such combos as Feint + Bullet Punch.
My tests show exactly the opposite. Quick Guard blocks Feint and any priority moves used after Feint.
EDIT: I've tried using Feint on both the actual user of Quick Guard and on another Pokemon on the team. Quick Guard blocks both and neither breaks Quick Guard.
Test #1:
Riolu, Escavalier, Basculin vs. Simisear, Simipour, Simisage
Escavalier uses Quick Guard
Riolu uses Feint on Escavalier, but it's blocked by Quick Guard
Basculin uses Aqua Jet on Escavalier, but it's blocked by Quick Guard
Test #2:
Riolu, Basculin, Escavalier vs. Simisear, Simipour, Simisage
Escavalier uses Quick Guard
Riolu uses Feint on Basculin, but it's blocked by Quick Guard
Basculin uses Aqua Jet on Escavalier, but it's blocked by Quick Guard
EDIT: Well, I've found one source of the discrepancy. I tried an Infrared Double Battle with Escavalier on one side and Riolu and Basculin on the other. In this case, Riolu does break through Quick Guard. The natural assumption is that this happens because the Quick Guard user and Feint user are on opposite teams, as poccil says. Although it's worth noting that Feint will break through an ally's Protect.
EDIT: Upon further testing, it appears that Feint will also not break Wide Guard when used on an ally. It'll do damage, of course, since Wide Guard doesn't block Feint, but it won't break the Wide Guard effect.
So, to sum up, it appears that Feint will remove the effects of Feint and Wide Guard if and only if the Feint is used on an opponent. This makes sense, since Wide Guard and Quick Guard throw up barriers between the sides of the field.