This is really fun to figure out! Everyone knows that nearly all Pokemon Gym Leaders have names which obviously reflect the type of Pokemon they use (Falkner does the bird thing, Brock uses Rock types, ect.) So, use your name to find out what type of Gym Leader you would be! If it dosn't sound obvious or have pop-culture connotations, (like Doug would be a ground type gym leader, Meriah could train flying types) Look up the meaning of your name and see if it hints at a type!
Example: My name is Marissa, which comes from the latin word "mare" which means "sea." My name means "the Sea" or "of the Sea;" so based on that, I'd be a water-type Gym Leader!