No actual Flashback aka Gardner Monroe in issue. The Master, Guardian, and Puck scene is just one of many flashback, future, and alternate reality scenes.
The only times I remember Guardian and Puck fighting the Master together were AF 130 v1 and AF 8 vol 4 but they were never together in same fight scene with the Master. So maybe this is an alternate reality scene? The closest scene I can recall would be Puck and synth Mac fighting a synth Master in AF 2 v2. Now I'm being nitpicky.