Mix smoked salt and white decorating sugar together on a small plate. Wipe the rim of a Collins glass with a lime wedge, then dip rim into salt mixture. Fill glass with ice.
Fill a cocktail shaker with more ice. Pour in tequila, lime juice, and mezcal. Cover and shake until very cold. Strain into prepared glass and add club soda. Slowly drizzle pomegranate simple syrup; the syrup will settle to the bottom of the glass, making for great color variation.
