Prior to the original Mario & Sonic at the Olympic Games, Nintendo and Sega had been discussing how to have Mario and Sonic appear together in a game for a long time, but had trouble coming up with a setting where both characters would fit. Ultimately, the Olympic Games was decided upon, as it was a setting that transcended both the Mario and Sonic series.
When Nintendo and Sega began work on Mario & Sonic at the Olympic Games, both were tasked with supervising the depiction of their own characters in the game. Nintendo would keep an eye on how the game depicted Mario and crew, and Sega kept an eye on Sonic and friends. This naturally led to some differences in opinion, regarding what was and wasn’t acceptable within the game.
One of these topics was with regard to swimming. Not only did Sega ponder the subject of whether or not characters like Peach and Mario should have to wear swimwear, Nintendo themselves rejected the early costume designs for Peach and Daisy. Meanwhile, the supervisor in charge of the Sonic brand at Sega wouldn’t budge from the fact that Sonic isn’t supposed to be able to swim at all, let alone take part in an Olympic swimming event.
Ultimately, both parties compromised. The development team ended up giving Sonic a lifejacket so he would be able to participate in swimming events, and later, during the development of Mario & Sonic at the London 2012 Olympic Games, Nintendo offered to draft swimwear designs for the female Mario characters themselves. Amusingly, the costumes designed by Nintendo ended up looking nearly identical to the original rejected designs Sega had proposed. This was because both company’s designers had felt that there was a very limited range of designs that would suit characters like Peach, Daisy, Amy and Blaze.
Different parts of the world reacted differently to the Mario and Sonic series as well. In Japan, Mario and Sonic is viewed as a party game, almost like an Olympic Games version of Mario Party. Meanwhile, in the west, it’s viewed more as a sports game series. European fans in particular, being fond of the Olympics, asked for more real Olympic events after the first game, as opposed to Dream Events, which are more fantastical.
Nintendo’s president points out that Europeans are also fond of horses. After the development of the original Nintendogs, people in Japan asked for cats to be included in the next Nintendogs game. Meanwhile, people in Europe asked for horses instead. This led to the inclusion of the Equestrian-show Jumping event in Mario and Sonic at the London 2012 Olympic Games.