I have a lawnmower in every tank and each tank also has a mix of gobies and blennies. never had any issues at all with the lawnmowers getting along with others. I can only say, be on the lookout for what the lawnmower eats, I had one who absolutely refused to eat anything but algae and actually died on me. Even with feeding algae sheets too so just take care that he gets what he needs.
__________________ 180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18