An otaku senshi is a sailor moon fanfiction character.
I have a lot, but most of mine are evil...sorry for the unrelated pictures...

If I had time and a good idea...

Well, I've drawn myself as a Sailor Moon character before, calling myself her little sister and wearing the same outfits.

(I knew a comment like that was coming...)
Don't put otaku senshis into 1 stereotype. Not all otaku senshis are like that. Well, maybe the ones by 6 year olds, but that's missing the point.

Well, I've never made a completely fictional Sailor Senshi. So would the correct answer be yes or no?

(Look up)

I have drawn myself as sailor moon before

@TigerRanma - I JUST found out what you mean. There are completley fictional senshi. A great example is Sailor Astera.
Her Deviantart (well, technically, it's the creator's) - link

I don't know is it otaku senshi, but I often imagine myself as Sailor Mercury and Dark Mercury. But, "my evil from", Dark Mercury is in Black Moon Clan, so she's maybe otaku senshi.