If they make a Mysterious Murasame Castle reboot, they could make Takamaru's character into anything, really (and also in Smash to an extent). Takamaru's almost like a blank canvas at this point, considering it's been a looong time since his game. I don't really mind what kinda of personality they give him, as long as it's kinda within reason.
Honestly, I kinda like Takamaru's character in Captain Rainbow -- I think it's adorable. I doubt they would pull any traits from that game, though lol.
Imagine... while everyone thinks Takamaru will have a loyal, honest, and caring personality, little do we know that Sakurai will make him a dishonourable samurai, making him practice Tsuji-giri on innocent civilians. Oh the irony. THE IRONY!!