I also have the same question. I'm mining XVG with lyra2v2 and my user parameter is an XVG address. So can we also collect these other coins (Ninja and Mona) somehow, or is it just understood that we cannot get them?
You are NOT "mining XVG".
You are mining Lyra2v2 and collecting a pay-out in XVG. Any ninja/mona/vert coins mined by the pool are split among the pool members, and your share is paid to you as XVG.
Look at it like this: You (and a thousand other people) are digging in a hillside that potentially contains gold, silver, and aluminum. Whatever you happen to find gets sold @market and split among all the people. You've opted to get paid in gold. You don't get any silver or aluminum. You could, if you like, opt to be paid in mushrooms... but that presumes that someone on another hillside in Zpoolville is mining mushrooms.