For info on how it works, see this image: https://dl.dropbox.com/u/9395043/Images/scarlet%20castle%20how%20to%20ig...
The entire arena battle is skip able if you're 2 or more players! If you are, one can just stand on the switch while the others pass through. This player can then go and die on the spikes or bomb blocks and be teleported to the next party switch, removing the need to do the arena shown in the image.
I'm pretty sure this is unintended so I thought I'd let you know.
These kind of tricks with statues and 2+ players can be done everywhere. An easy example everyone misses is the first level of RJP.
BUT by doing these stuff you lose all the rewards from the monster you would have killed, and demands a sacrifice, so meh, why bother.