I see that using the phrase "Nico-nico-nii" is not allowed here due to various reasons, like this. So, are there any ways to use this phrase in a good/valid way here?
In what circumstances would that be something that could help answer a question or solicit discussion? The only time I could see this being valid on MusicFans is if it were part of the lyrics of a song, but that hasn't been the way we've seen this being used in the past. That's a phrase that simply has little potential to be constructive on this (and most other) Stack Exchange sites.
Realize this: Stack Exchange is not an entertainment website. At its core, it is a Question-and-Answer Database, meant for serious discussion and empirical research. Humor and inside references are usually not acceptable within the site's important functions, such as Questions, Answers, Edits, Flagging, Votes-to-Close, and others. Comments and chat are less restrictive, but there's still an expectation of not simply posting troll garbage on the site.
If you can find a way to be comedic within the site's intended functions, by all means, be my guest. Personally, I love seeing that human element expressed on the site. But that doesn't mean I'm okay with random junk in the comments or (ahem) clogging up the moderators' flag review queues, and I think the community is 100% behind me on this one. Take your anime references elsewhere, please.