Now, my idea was that the stage wasn't going to be entirely centred around Spiderweb Island, but also take elements from all of the other "spooky" locations from throughout the series. Hypno Baron's Castle, Zombie Caravan, Mud Bog Island, etc. The main layout, and aesthetics of the stage though, would be mainly based on Spiderweb Island.
I was thinking that the stage could contain multiple different enemies (maybe an amount, similar to Dracula's Castle). Ikki, the Slimegals, Ghosts, Zombies, "Those Purple-y, Bouncing Gooey Things on Mud Bog Island"...
I could also see Rotty's Wagon becoming a stage hazard, functioning similarly to King Bulbin on the Bridge of Eldin stage, rocketing across the stage, with Poe at the reins.