To be honest, I do kinda feel upset of seeing Takamaru placed as nothing but an assist trophy, to me. What an assist trophy is... It's something that I think is meant for a character that has his/her franchise already represented with a character. Take for example Punch-Out, Little Mac happens to be a playable character, so having a boxer from his game wouldn't hurt his franchise. As it can branch out to his franchise further and showcase a character that perhaps does not fit the requirements to be a playable character.
Now with Takamaru, I find it difficult to see him as an assist trophy, as he's the only character from his franchise. And keeping him as an assist trophy would only make his game lesser known, compared to the playable characters. Personally I would love for him to be playable instead, as having him in Super Smash Bros could lead to further possibilities with the retro cast.
That is how I see it.
And not to mention, it can even lead to more paths to open for Takamaru and his franchise. If you look at Pit and Kid Icarus for example. As you know, Pit wasn't very well known by the time he was announced in Brawl, but in due time. When Sakurai decided to make a game for Pit, more people got to know him and his background a lot more. Which is a good thing, and something I want to see happend to more retro characters. Yes that includes Takamaru as well.
Before I forget, I personally love seeing more retro characters represented in the playable cast, rather than assist trophy, while it is nice to see some of them as assist trophies. I do not think it is the right fit for them to be there. But that's just my opinion and how I feel of the situation.
Either way, I do fully support this thread, and I hope more things can come out of it!