Nintendolife
Yoshi would have enjoyed the company
http://www.nintendolife.com/news/2012/03/donkey_kong_and_pikmin_could_have_had_cameos_in_super_mario_galaxy_2
Gamespot
Shigeru miyamoto shot down guest appearances from iconic nintendo characters in plaformer sequel, saying they did not have a functional reason to be included.
http://www.gamespot.com/news/donkey-kong-pikmin-super-mario-galaxy-2-cameos-nixed-6365948
Stadium Arcadium
Stadium Arcadium
http://stadium-arcadium.com/forum/viewtopic.php?t=29079&sid=c8ab4b0d88135b85f6a2a1227ecc0269
Reviewsontherun
Reviewsontherun
http://reviewsontherun.com/all/spotlight/randy-van-der-vlag-video-cameo
Elecplay
Elecplay
http://www.elecplay.com/all/spotlight/randy-van-der-vlag-video-cameo
Mariowiki
Mariowiki
http://www.mariowiki.com/Cameos
Zappinternet
In one episode mario appears and make a parody of the videogame donkey kong.
http://www.zappinternet.com/video/DuSzJogRux/Simpson-Super-Mario-cameo
Wario Ware
Wario Ware
http://www.warioware.biz/