Scales to Play Over Gm
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.
A Gm chord contains the notes G – A# – D. Any scale that includes every one of those 3 tones fits over it — from the root G, that means G Natural Minor, G Melodic Minor, G Harmonic Minor, G Minor Pentatonic, G Blues, G Rock 'n' Roll, G Dorian, G Phrygian, G Dorian Bebop, G Half Whole Diminished, G Gypsy Major and G Gypsy Minor. Start with the first scale listed: it is the most common choice, and the others color the same chord tones differently.
Gm is also diatonic to 3 major keys: A# major (relative minor Gm), D# major (relative minor Cm), F major (relative minor Dm). In a song from one of those keys you can also solo with the key's own major scale or its relative minor pentatonic across the whole progression, not just this chord.