I agree I used the 3 sannin and with substitution and their specials I beat it on the first try. I saved the extra stuff (team bonus stuff)*for the last battle so it made itachi and kisame real easy. one thing I can say is use Tsunade because if your running low on health you can use her special and regenerate all your healthjust remember to refill your chakra every chance you have so you don't run out and you want to beat them before she gets the age stat
the way i beat the insane stage was to not use the skills until the last stage, so you have more of an advantage. i did it with team kakashi, so i suggest at least saving the Sexy jutsu skill, the will of the fire and the chidori until the very last stage. winning without skills is hard, but if you practice on the easier stages, it gets a lot easier.
I think that it is safe to say that most people beat insane mode using the sannin. I think this is because they are th easiest to beat it with. I used the sannin the first time I played and i did have some trouble in the middle but the rest is easy.