But yeah, my first thought as well. The longest-running web series on the internet! :)
I know the word gegen is for against. Could someone please tell me if this phrase may also be a possible interpretation "Red on blue",? I am thinking as in terms of contrasting colours.
Why in this sentence rot and blau are not nouns, when in Sie mögen Rot, Rot is a noun?
Which dictionary does the Duolingo team consider an authority? I see several suggestions from months ago that vs. should be accepted as a substitute for versus. If we can please be on the same page I wouldn't have the constant feeling that Duolingo picks and chooses weird acceptable variations. Vs. as far as I know has ALWAYS been a substitute for versus. I rarely see it spelled out.
That said, anecdotes are not helpful. Give us a dictionary Duo to refer to during these disputes and I might reconsider quitting this program.