very good
You said not to compare it with the others so I won't. By prolonging the boss combat, one way would be to do it similar to XiaoXiao where you can see the boss backing away and is trapped. Losing a limb (arm) or two in combat is good too where combat continues and the hero(heroine?) still finds the boss a worthy opponent.
The boss is not that "rough." Boss combat should threaten the hero within an inch of his(her?) life and be right on top of the player every second even though they are not ready yet.
Refer to XiaoXiao for good boss combat.
Naturally the Poninjas are your own and rightfully so. You do what you feel is best.
GREAT JOB on getting the -MMM- frames/sec. animation and lightning fast movements. That is your greatest asset. :)
David