Just a note: Freezi 'can't' do it because most of the higher levels did it already in Kirameki.. Which sucks for him x_x The ones that did the quest already can't help with the scenario quest anymore, but can help later on with normal princess.
And, it worked fine with a lv 70 sword knight, and a lv 80 spear warrior. However, the warrior had fashion shop pots to use when it was really needed. I, as a level 59, was just standing back. ;o
So yeah, just giving the tips which could work too.. What they did was attack each on one side, and when their hp was getting alarming low (the one that tanked) he would duck so Princess would attack the other one. Etc.
Thank you so much k0n <3