The majority of the puchimasu! tag (1314 out of 1621 posts) is by yuureidoushi who adopted the same type of chibi style for his own comics, all of various copyrights but not of idolmaster. Of course it's easy to just search puchimasu! idolmaster since puchimasu doesn't imply idolmaster. But that raises the question, at that point should it still be tagged with the puchimasu copyright when it doesn't feature any of the puchimasu characters, or parody any specific moments? I was thinking there could instead be a puchimasu!_(style) tag that doesn't necessitate using the copyright. If that were done then it would be possible to have puchimasu imply idolmaster as well, if anyone thinks that would be useful.
There might be some precedent for creating a style tag named after a copyright, the majority of style parodies seem to be named after an artist but list_of_style_parodies lists a few style parodies by copyright.