There we go again with double standards. "He doesn't count as relevant because he hasn't had a new GAME, hurr durr."
Doesn't matter. Relevancy is relevancy. Takamaru, for all intents and purposes is an old character with relevancy.
Otherwise, characters like Foreman Spike are relevant just because the Mario series is a relevant series.
If you have to make up an excuse in why that doesn't work, it's a double standard.
So in summation, there are relevant characters and relevant series. They are not one and the same.
Takamaru is rather relevant, but Murasame Castle, the series he comes from, hasn't been relevant.
The Mario series is obviously relevant, but Foreman Spike, an old character not seen in at least a decade, is an irrelevant character.