#675 - Swimming With Shoes

All characters from Mario & Sonic at the London 2012 Olympic Games were going to have swimwear for water events. However, this was rejected by Sega, who stated that "Sonic can't take off his shoes". In the end, only female characters had swimming gear.

SOURCE: https://www.shacknews.com/article/71640/how-mario-and-sonic-get-outfitted-for-the-olympics