OlliOlli World

Sidequests are available on levels with a purple diamond above them. Then once you are playing that level, look out for when the game slows down and prompts you to press . Once you do so, you will talk to a character. After talking to them, complete the rest of the level (or back out), and you'll now notice on the map a purple diamond level for the sidequest. These are typically mini challenges where you have to do something in a certain time limit. There are 2 for each area. So, simply complete all 10 side quests and you will unlock the achievement. None of them are really difficult IMO, but the only ones that gave me a bit of trouble were any of the ones involving laps. So, it just may take you a few tries is all!