Heres how to defeat the kerchu. First hop on the girnd rail. jump over the green fire and the gaps. Then you will end up on a square shaped platform. Don't worry if you fall. There is a floor you can land on. It's easier to defeat him if you jump off the square onto the ground. But it will cause the kerchu to send out the spike ball kerchus. Keep shooting the kerchu as much as you can. Remember the groovation device is very useful when you're surrounded my enemies. All you really have to do is keep shooting him. You can contact me if you need more help.