Very fun and the story has me really interested with all of the cross-overs going on! Popple knowing Crump was very exciting to hear about. The only thing that I was disappointed about was the fact that Popple actually had the Passport. When he stole it, he was a darker shade. I was expecting that to have been a Dark Popple, created by some greater evil in waiting.
That being said, the combat was surprisingly smooth, much like the original RPGs themselves. The only suggestion I can really give you, since you say you will be adding other ways to attack in the upcoming game is that you make the combat menu able to be controlled with only the keyboard.
I guess one other thing I should ask about is the possibility of controlling both party members. In this case, that would be the rescued Yoshi from the Glitz Pit. It felt very strange not controlling both party members in a game so much like the Mario & Luigi games. That would smooth out whatever bumps are left with this awesome game.
Good luck with this series, and I hope it does well!