That is debatable. A lot of people say that you can have them in a community....but from my experience, my yellows would like nothing more than to tear a platy to shreds....seriously...they are very aggressive. Always mating. Maybe if you got only females, but I also hear that yellows can have a matriarchal dominance over a tank. Also being very murderous. These are just all opinions and experiences of mine, feel free to try it and tell us how it turns out. Just be very watchful....and have an extra tank ready for when you need to seperate them, if you do.
:edit: forgot to mention that yellows get to be about 10x the size of platys too.
im moving my plattie to another tank and im going 2 get 2 labs. just to see how they are. i know they need a bigger tank then whati have but ill be getting a bigger 1 soon.
Bear in mind that the PH in the tank is going to need to be around 8.0 for the Labs to feel at home and that might not be ideal for the other community fish.
i think it is already 8, and i decided not 2 get 1 because some1 gave me a zebra cichlid, so i guess ill just have that 1. i still really like the labs, so maybe in the future ill be getting some.