you need a team that will allow you to win, despite being severe underdog.

how i used to do it is start the day with survival, get as far as i can, if i stuggle i retreat (so i dont lose any ninjas). Go train and then hopefully im stronger by the end of the day.
Doesnt really work anymore at higher levels... too hard to power up significantly.

anyways. my kabuto, sai, kakashi, lightning main guide has helped me win many battles where the opponent is like 2k power more than me.