Unless you hear he voice in the anime. then you can definitely tell she is a girl. also, Takato has mention it so many times when he has referred to Guilmon as a he. So, while Renamon Says that they have no gender, She is wrong
you dont need lips to eat,talk(helps a little in our way to talk, but is not needed). and yes, i was in a way wrong, the canines(wolfs,dogs,fixes,etc.)have lips,yes, but is not like ours, if a renamon put herself lips paint(i dont remember how is sayed in english) wont leave that print, and kissing wont be like kissing a human.
this draw is Awsome, but im only saying that is Thecnically incorret.