Don't know what else needs doing to the MK pit.Based on your image, i haveLengthened the floor. Inserted the thing with the bean squid head bit as part of the floor (no idea what that was for) added the additional animations and moved some people around. Raiden is now on the floor for example.The large spikes move slowly across the screen in the background and gradually bob up and down as if floating in something.I sorta feel like the stage as a whole should be longer. But that's about all i would suggest for it.
I can lenghten the floor sprite if you wish or feel it should. do you want me to add new characters to it?( imma changing my method, gonna make a thread per stage, I guess it will be better)