No need to worry, I already fix the XD error. was not your plugin but my skins because none of them had the "inspect" because I had downloaded a package of weapons any of youtube and forgot to save your skins in another folder haha sorry for that mistake. but finally let's forget it, ok, I'm just anxious, how much will the Molotov plugin go out ??
I can only assume that your either using a outdated version of SD Cafiine or there was an error in the file copying process. I can't say that I've tested the pack on the previous wii U version, but it should would regardless with the newest version of SD Cafiine. If you haven't, try both of these methods first and then try running the pack again.
If you want, you could make a bunch of Waluigi's show up by editing the individual stages' item_common_param files and changing the item ID for another item to Waluigi's. Then Waluigi would randomly spawn on that stage. There's a couple of modpacks that do that.