I know it can be frustrated, been there done that.

If you have watched video(s) how to beat ninja exam "this"

Firstly you need to annnnnnnnnnnalyse how this person beat the exam.

If you don't have the same ninja. Try to create your own team with similar buffs and chases.

Timing is also crucial in some exams, i.e. when to use mystery. Even though you have exact same team, but you didn't use mystery at right timing, result would be different.

It's called "exams" for reasons.

p.s. censor words can be annoying sometimes ==