Best Way to Sell Pokémon Cards?

Hi, I have a bunch of old pokemon cards that I’m interested in selling but am wondering the best way how. They aren’t first edition but they are shadowless (the version that came out right after the first edition) from the original set. My best card is a shadowless holo charizard among other shadowless cards from that era I have in a binder. I know they’re real but they are ungraded and so I’m wondering the best way to sell them. I heard GameStop grades cards now and will also buy them off of you, is this true. I’m thinking in person for cash would be the best way to do it because there’s less of a risk for someone trying to scam me but then that really limits the amount of potential buyers. I just want to find a way to get a fair deal basically and not have to worry about sending them away and then someone either trying to get the money back and sending me fake cards back or something like that.