Bring sugar and water to a boil in a small saucepan; stir until sugar is dissolved. Remove from heat, stir in mint leaves. Let steep for 10 minutes. Remove mint leaves.

In a blender, combine watermelon, lime juice, tequila, and half of the mint syrup (use more if you like a sweeter drink). Blend until smooth.

Divide into 2 glasses filled with ice. Garnish with mint leaves and lime wedges.