Scales to Play Over Adim7
Every chord is a subset of several scales: any scale that contains all of a chord's tones fits over it. Pick a chord to see the matching scales from its own root, the major keys the chord belongs to, and full fretboard diagrams for every scale on guitar.
An Adim7 chord contains the notes A – C – Eb – Gb. Any scale that includes every one of those 4 tones fits over it — from the root A, that means A Half Whole Diminished, A Whole Half Diminished and A Gypsy Major. They differ only in the notes between the chord tones, and that is where each scale gets its color.
Adim7 is not diatonic to any major key — it is a chromatic color chord, so treat it as a moment of tension: lean on its chord tones from the scales above, then resolve to the surrounding key when the progression moves on.