Run a lime wedge around the rim of a cocktail glass. Dip into the lime sugar, shaking off excess. Fill with ice.
In a shaker, muddle the lime juice, mint leaves, agave, and pineapple juice/chunks. Add the tequila, mezcal, and Cointreau. Fill the shaker with ice and shake until cold. Strain into the prepared cocktail glass and garnish with a pineapple wedge and mint leaves, as desired.
Notes
*Lime sugar: On a shallow plate, toss together 3 tablespoons of sugar with 1 tbsp lime zest.