i feel like magireco tends to do this based on color if anything because i feel like i have a hard time getting a definite idea on what classifies a character as xyz element buttttt
light - aether, ellie
dark - lillian
forest - willow, teles, aster
aqua - celeste, valerie, yuki
no void because that has specific classifications (if someone had to be void i think aether or yuki could probably make the cut here) and no flame bc none of them are red enough