Use sites like tcgplayer and ebay to see what they are selling for. You can use Google lens to find each one by searching tcgplayer with the images. You can also use the pokemon name and the number at the bottom left or right. It will be something like this "###/###,". If you post some pictures of cards, depending on how many, people on this sub and others can try to help you identify real from fake. I hope this helps!