Im not trying to convert anyone, but objectively, Takamaru is a sensible retro character addition.
In 1986, Nintendo released four major titles for the new Famicom Disk System peripheral: The Legend of Zelda, The Mysterious Murasame Castle, Metroid, and Kid Icarus. The Nintendo EAD departments main title was The Legend of Zelda, and Nintendo R&D1s main project was Metroid. Murasame Castle was built using the Zelda engine, and Kid Icarus was based off of the Metroid engine.
Just looking at Murasame Castle next to Zelda, the similarities are immediately apparent.
The game was also scored by Koji Kondo, who did the music for The Legend of Zelda.
Nintendo of America figured Westerners wouldnt be interested in a game based on feudal Japan so it never saw release outside of Japan. Had it been localized in 1986, theres no doubt in my mind that the game would be regarded as a classic and that a ton of people would want Takamaru in Smash Bros.
People who arent familiar with the game deride Takamaru for being just another swordsman, but that isnt the case. Not only are there no samurai-style characters in Smash Bros., but Takamaru uses shuriken, he throws fireballs, he can turn invisible, and he can even summon lightning.
Also, a fun fact: The Mysterious Murasame Castle was adapted into a live action TV drama in 1986.