From the Super Mario Wiki, the Mario encyclopedia
Bowser's Blues (also referred to as Wild Ones Bonus 1 and Wild Ones +1) is the first Wild Ones bonus episode in the Story Mode of the Nintendo 3DS version of Mario & Sonic at the London 2012 Olympic Games. The episode is unlocked after completing Junior Triumphant!, and unlocks The Life of a Minion once it is completed.
Bowser, Lakitu, Magikoopa and Goomba are out sightseeing in London. Lakitu tells Bowser that London is the City of Light, though Bowser angrily corrects Lakitu that Paris is the City of Light and London is the City of Fog, and Magikoopa tells Bowser that the Tower of London is Big Ben, though Bowser once again angrily corrects Magikoopa. The minions notice Bowser's mood, and thinking that he is nervous about the Olympic Games, they try to cheer him up. This makes Bowser even angrier, and causes him to head off to get some rest. The group decide that they could cheer Bowser up by helping him to win one of his best events, and head off to bed so that they can get up early to prepare. The next morning, Magikoopa meets with Donkey Kong at the Main Stadium and asks him to compete with Bowser in an Olympic event to try to cheer him up. Donkey Kong refuses, though Magikoopa tricks him into believing that he will paid with a large pile of bananas. Donkey Kong attempts to collect the bananas, though he is knocked out by a Thwomp, and Magikoopa makes the bananas disappear. Bowser arrives with Lakitu and Goomba, and Magikoopa tells them that Donkey Kong is preparing to ambush Bowser and challenge him to an Olympic Event. Bowser agrees to challenge Donkey Kong.
Bowser beats Donkey Kong, which cheers him up a bit. Donkey Kong is initially angry with Magikoopa, though Magikoopa promises to get him some bananas, and the pair head off. Lakitu and Goomba tell Bowser that Knuckles and Vector are waiting to challenge him at the wrestling venue, and although suspicious of what the minions are up to, agrees to see them. Lakitu heads off to prepare, while Goomba accompanies Bowser there.