Nintendo has launched a pretty substantial website in Japan for Mario Party 10, which arrives on Wii U rather soon, and some details and images have prompted speculation that more unannounced Super Mario range amiibo toys are on the way.
As you can see in the image below special boards for Rosalina, Donkey Kong and Wario - a previously confirmed amiibo feature - are shown alongside simulations of new amiibo toys for these characters. Before now Nintendo has stated that the equivalent Smash Bros. range toys will be supported, but this seems to be the first time that visuals of potential Super Mario amiibo have been seen.
It's worth noting that on the relevant page the interactive amiibo links show the Smash Bros. figures, with these Super Mario-themed mock-ups then appearing in the subsequent image on the right. As a result it may be merely conceptual, but in light of Nintendo's eagerness to release as many amiibo variations as possible we wouldn't rule them out. We suspect the Rosalina toy would be in particularly high demand, primarily due to the Smash Bros. variation being hard to find.
There's also a character roster (including the confirmed amiibo characters + Daisy and Waluigi) that has two empty slots with question marks, though we could reasonably expect those to be filled by fairly standard Super Mario characters.
The website is packed with screenshots so is worth a look - as for these potentially new amiibo, would you try and pick them up?
Thanks to Dan H for the heads up.