Bring sugar and water to a boil in a medium saucepan, stir until sugar is dissolved. Remove from heat; pour off all but one cup of syrup, reserving any extra for another use.
Heat the syrup to a boil and then reduce heat to medium. Add the cranberries and simmer for 2-3 minutes until they just begin to burst. Remove from heat and let cool in syrup.
Place 2 Tablespoons drained cranberries and 6 Tablespoons cranberry syrup in a large pitcher; add the lemon wedges and orange slices.
Using a muddler or wooden spoon, vigorously mash the fruit. Then stir in gin and let steep for at least 5 minutes.
Fill 4 glasses with crushed ice and 1/4 cup ginger ale.
Fill a cocktail shaker with ice and then pour half the cranberry mixture into the shaker and shake vigorously for 10 seconds, strain liquid into two glasses. Repeat.
Mound additional ice on top of each glass and garnish with 3 candied cranberries and a mint sprig