2 (0.13 ounce) packages unsweetened lemon-lime flavored drink mix (such as KOOL-AID®)
2 cups white sugar
8 cups cold water
1 (46 fluid ounce) can pineapple juice
1 (2 liter) bottle lemon-lime soda (such as Sprite®), chilled
Mix lemon-lime drink mix, sugar, cold water, and pineapple juice in a large bowl until sugar and drink mix have dissolved; refrigerate until cold, about 1 hour.
Gently stir lemon-lime soda into the punch just before serving.