Anonymouse currently uses the Gen 6/7 Raichu Cry, possibly suggesting that Anonymouse is a Raichu in disguise.
Its cry also mentions the phrase "We do not forgive. We do not forget.", a reference to the Anonymous meme.
Its Dex entry is a reference to a Reddit post on r/atheism that has been widely mocked. The full quote is "In this moment, I am euphoric. Not because of any phony god's blessing. But because, I am enlightened by my intelligence."
The group 'Anonymous', the character "V" from "V for Vendetta" and the anonymous guise chosen by the aforementioned group, and a Mouse. Its shiny is photo negative.
Anonymouse is a cross between "Anonymous", meaning to go unknown, and 'mouse'.