Every fingering that fits a hand
0035
easy
0233
open
x785
easy
ccaa
hard
ccax
easy
What is true of it
Gsus4 is G, C and D — 1, 4 and 5 counted from G.
These are also the notes of Csus2/G. Which name is right depends on what is underneath and what came before — the notes alone do not decide.
The easiest of the 5 fingerings below is 0035: 2 fingers, held at the 3rd fret.
1 of them use open strings, which is what makes a shape quiet to change to.
Where its notes are on the neck
The brass dots are G, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Gsus4/C
5035
Gsus4/D
x233
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.