Here is the full list of all 13 Old School Musical achievements.
A like Almost (A on all hard levels)
Ok, but everybody can do that (B on all hard levels)
Chicken Republic seems to be too easy.
If you keep retrying this level, you will succeed
Losing 5 times in a row in easy mode ? Really ?
Failing the best grade with only one mistake, it's sad
You deserve this reward for your patience with Mehdi
We give you this but please leave Matt alone
So, the controller has buttons, you must press them
It starts getting serious (A on all main score hard levels)
Could be better (B on all main score hard levels)
You finished the story mode. Spoiler : everybody dies.
It's nice to talk to everybody