Very Good
Allow me to begin by saying that this is a superb flash animation. However, being the fanatic that I am, I have found a couple of things that could be changed to improve this magnificent flash.
First of all, in my opinion, you should have used the uncensored Japanese version with blood and everything. But then again, that is really a matter of preference and availability.
Second, you made Zero’s voice too deep and from what I can tell, you tried to make Kyubit Forxtar a girl. Believe it or not, he is not a girl. Like Tenguman from the Classic Series is based on the tengu from Japanese mythology, Kyubit Foxtar is based on the old Japanese legend of where male fox spirits turn into beautiful women to lure monks away from the temples. However, like proper women is Japanese culture they do not speak. This is convenient since they still have the voices of men.
The animation with Leviathan disappearing not only doesn't flow well with the rest of the animation, but it also is completely unfounded by the games.
Last but not least, the title is inappropriate since it is not the last cataclysm. Otherwise there would be no Dash (Legends in the US) Series. Unless the Zero Series ends with the world being destroyed, it is not truly the last cataclysm.
Regardless of all my criticism, the flash is beyond great. It is absolutely superb, and I look forward to more of your work in the future. Oh, and incidentally, I think you should definitely include Unknown X/ Cyber Elf X/ Original X/Cyber X/ whatever you want to call him in the sequel. After all, itt wouldn’t be Rockman Zero without a Rockman! ^_^;