Paper Mario is one of the more unique franchises in Nintendo's library, thanks to the interesting take on visuals. While the paper aesthetic is standard now, it was pretty much a brand-new idea when the original Paper Mario launched. Turns out the game wasn't always going to use a paper approach, though!
A classic interview from 2000 gives us some insight into the other visual styles considered by Nintendo. The comments below comes from Ryota Kawade, Chief Director (Intelligent Systems) and Hiroyasu Sasano, Technical Support (Nintendo).
Sasano: One thing we decided early on was to make Paper Mario less of a sequel to Super Mario RPG, and more of its own thing—a brand new RPG featuring Mario. To that end we consciously distanced ourselves from the stylings of Super Mario RPG.
We spent close to a year and a half trying out different character ieas. We also tried using pre-renders like SMRPG, but we figured it would be more fun for us to attempt something completely different this time, and that paper-y Mario was the result.
Kawade: Yeah, we tried polygons, but there was too much overlap with the N64 Zelda games, I guess, so it got rejected. (laughs) We were using Silicon Graphics as a software tool, but ultimately we ended up dusting off those old Super Famicom tools and using those to create the Paper Mario graphics. (laughs)