I really love this game but I have a couple of questions:

When playing challenge mode, if I unlock a skin...can I play that skin anytime I want wihtout having to go through levels?

For versus CPU mode, is there a retry? Or can I start playing at the level I last left off? Or can I choose which cpu oppeennt? For instance, I get to the second level(after the Jungle/Lion) and I usually loose...but I'm not given the chance to retry and I have to start at the first level(The jungle/lion level) all over again.