Scales to Play Over Gsus2
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 Gsus2 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 Major, G Natural Minor, G Melodic Minor, G Harmonic Minor, G Major Pentatonic, G Rock 'n' Roll, G Dorian, G Lydian, G Mixolydian, G Dorian Bebop, G Mixolydian Bebop 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.
Gsus2 is also diatonic to 5 major keys: A# major (relative minor Gm), C major (relative minor Am), D major (relative minor Bm), F major (relative minor Dm), G major (relative minor Em). 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.