Is caffeine present in all chocolates and chocolate drinks? Does 'serious mass' weight gainer contains caffeine? Thank you.

Dark chocolate. Caffeine is higher in dark chocolate than milk chocolate. Any of the serious mass weight gainer that is chocolate would contain some caffeine. Red bull is 80 mg of caffeine per serving and caffeine in milk chocolate is about 12 mg. ( red bull is 7x the caffeine of regular chocolate) it might help to cut back on red bull.
Analogue. Theobromine is in most chocolate, which behaves similarly to caffeine, which may also be present depending on food/drink. You need to check labels to see if says contains caffeine. Especially if added, will say on label.