I think this limitation is intentional to keep it from being real easy for distribution of copyright protected material (WotC, Paizo, Evil Hat, etc.). Character sheets shouldn't be an issue. While you can't use the transmogrifier, you can still easily use the character vault to move things from that game to one of yours. As long as you have edit permission, they should be available to import to your vault, and then export to one of your own games. Then the transmogrifier will apply, since they would then be available in one of your games. If this is a custom sheet, then you should be able to use it just fine as long as your friend gives you the html and css files to plug in. You just need to set the sheet for your game to Custom. If the character generator uses rollable tables, I think there is a script that can help with this. I'm fairly certain I have read of one that can export/import rollable tables. Hopefully someone else will post more about that, or you will be able to find it. I've never used it, so no personal experience to share. Decks... you may have to rely on getting the images used from your friend and building them in one of your games. Maybe someone else would know of an easier way to go about that, but I don't know of one.