I have a Gliscor card from the Rising Rivals Pokemon set which says it's an 'Elite Four's Pokemon' but on the top left-hand side it's written GL (Gym Leader) instead of the usual Elite Four icon (see picture below). Would this be a misprint?
This is a fake card.
Pokémon maintain a high quality of their manufacture process. Even though it is possible that misprints are produced, they are usually either well known or they are just printer errors, not problems with card design itself.
Your card uses different fonts and text is not aligned and spaced properly. These problems indicate that the card can't be a misprint.