Kid finds out that when puberty begins for them they get super powers.
Problem is, the super power they have changes from day to day.
Not a 24 hour cycle, more a “when you wake up after sleeping” type deal.
So every time they wake up they have a new power, which they have no idea what it is until they use it and have very little control or mastery over the skill.
Monday, wake up with Hydrokinesis. Accidentally “wet the bed” with water powers. Parent comes in, sees bed is wet, kid is embarrassed.
Next day, Tuesday, wake up with Pheromone Manipulation. Now dorky un-popular kid magically has become the most admired person in school only to lose it on…
Wednesday! Wakes up with giant bird wings (eg - Archangel) and has to wear a large trench-coat to cover them up, making the kid look incredibly suspicious to everyone which makes all the progress of “being cool” they made the day before completely disappear.
There is a potential for repeat powers, which would probably be a blessing or a curse depending on the power.
Once the character reached the end of puberty, they would be allowed to choose one of the powers they had used to be their only ability throughout the rest of their life…or choose to have no powers and go back to living a normal life like they did before it all started.