You must not have looked through the threads very hard, because Amopakamu has posted the formations he's been using on the Ninja Exam up to Exam 81. And yes, he's an Earth Main.
Here's the thing - when you get up to the high 50s/60s in level, you can't just brute force your way through instances and exams and trials the way a lot of people do as low level players. The game is designed to draw people in, so the first 30-40 levels is a piece of cake. Moving beyond that, it takes more time and skill to craft good teams and considering the addition of new abilities, summons, and other aspects that make the game strategically more interesting. This is exactly why Ranked and Arena hides your opponent's lineups - and if you lose, so what? Just try again.
Normally I wouldn't comment on a thread like this, largely because I don't play as the same main, but the problem I have here is that you're asking for someone to hand you the answer on a silver platter, when as a Lvl 66 player you should have the experience to figure it out yourself.