i feel like the understanding 'this character must Have A Flaw to be relateable' is how we get so many pretty perfect female characters who are clumsy in a way that contributes nothing to the story. so many writers seem to go 'oh, this character is too perfect. how do we make people like her?' 'make her trip over!' 'gasp....... youre a genius!'
all characters need to face a challenge, and all characters need to develop. and this necessitates 'flaws'; characteristics, methods, or values that hold them back from their goals, which they must change. if they dont face any challenges and dont change, whats the story?
say youve got a superhero called... uh... soup-man. hes got super strength, lazer vision, super speed, the works. nobody can fuck with him. no-bod-eeee. giving him the flaw 'has wind' or 'cant do math' is worthless if it doesnt contribute to a story where he changes. interesting character flaws would cause him to fail in his goals; maybe he gets cocky, which leads him to lose his powers, and then has to learn to overcome his pride and accept help from others. maybe he feels such an responsibility to save lives that he burns himself out, and needs to... uh... learn to overcome his pride and accept help from others. those are flaws that facilitate change.
that said, 'cant do math' could be a good flaw if he finds that while he is super strong and can fight anything, he keeps getting outsmarted by a particularly mathsy enemy.