A grande strawberry açaí refresher is about 90 calories and 20 grams of sugar; the mango dragonfruit is similar at roughly 90, and the pineapple passionfruit nearer 80. They get their lift from green coffee extract, about 45 mg of caffeine per grande.
Iced teas split two ways. Sweetened or lemonade-blended versions are 90–190 calories; a plain unsweetened iced black or green tea is effectively 0–5 calories with 25–45 mg of caffeine.
So the lightest café order that still tastes like a drink is an unsweetened iced tea; refreshers are the lighter *sweet* option. Adding lemonade to either moves it into the sweetened bracket immediately.