Sonic and Mario worked together for a long time, brawling it out in Smash Brothers too playing the Olympics together. But what about a platforming adventure?
“Actually, I wanted Mario [and Sonic] to appear together, so one time I went to give Miyamoto-san a presentation on how I want to create an action game which is co-starred by Mario and Sonic. It was in the GameCube days, and I took around four planners with me. It is a pity that the discussion was ‘clearly it isn’t necessary for Mario and Sonic to co-star in an action [game]’ and it didn’t become a reality, but SEGA was able to get the license for the Olympics just at that time, so in order to make the best use of the license, companion characters appeared together. A little later Sonic appeared in Super Smash Bros. Brawl. However, this too came into reality because I requested from Sakurai-san, ‘I want Sonic to appear [in Smash Bros.]’. The Olympics is a bit different from my wish, but I think it’s a good thing that children around the world are happy about them co-starring. But someday I want to realize an action [game] together with Mario. I think I’m going to give another presentation so that Takashi [Iizuka] finds the necessity [of a Mario & Sonic action game] (laughs).
“I also agree. Previously they were considered rivals, but when I saw them co-starring, I honestly thought that Nintendo acknowledged Sonic.”
Original Sonic designer Naoto Ohshima
Both of the fathers of Sonic show interest in a proper platforming adventure staring the two gaming icons happening. With Nintendo & SEGA having a good relationship now, it could happen in the future.
Source: My Nintendo News