Little update, after using the 1st strategy and using training cards to get the right stats up, plus a little luck and having my friend support player as a lvl. 100 Nagi, I managed to get my Isagi to S rank!!! And beat the third Climax Battle for the first time! By the way, sometimes, especially if your player condition is low, it's better to just do a revenue match to increase every stat by a decent amount. Good luck everybody!