Takamaru Originally Planned as Playable in Super Smash Bros
Who is Takamaru, you ask? He's the protagonist of the Famicom classic, The Mysterious Murasame Castle, and according to a recent interview with Super Smash Bros. creator Masahiro Sakurai, he was originally planned to stand alongside heroes like Mario, Samus, and Mega Man in the newest entry in the series.
While the reaction of the Japanese Super Smash Bros. fanbase would probably have been pretty positive for the inclusion of Takamaru as a playable character, English-speaking fans would likely have been less than thrilled. Takamaru doesn't exactly have what you'd call international appeal, since he's from a 30-year-old Japanese exclusive that very few people played in the West. Most Western gamers have probably never heard of the guy, and would begrudge his inclusion at the cost of not having other, more familiar faces like Solid Snake, Paper Mario, Birdo, Knuckles or Captain N: The Game Master.
Smash Bros. fans are notoriously passionate, and they all want their own favorites to be included in this legendary fighting franchise, so the addition of an oddball playable character like Takamaru probably would not have gone over well. Ultimately, however, Sakurai decided that, though Takamaru lacked the international appeal to make him worth it as a playable character, he was important enough of a character to include as an assist trophy, so you can still see him in all his baggy pants-wearing glory.
For those of you Smash players who are ravenous for some new characters, try to sate your hunger with the knowledge that Mewtwo's coming, and he's coming soon.