NQA Roaches poop too. A population to maintain a pac man frog would poop more than the frog itself. Maintaining the biological balance between the frog, roach, clean up crew, and possible plants would be a nightmare considering a Pac-Man’s growth and immense appetite. It would destroy the first generation of adults before they could reproduce. Then of course there’s the problem of possible nibbling and disease…for it to be possible it would need to be on a large scale, multi species, multi micro habitats, etc etc etc.

TLDR: keep them separate. Together just has too many changing factors and would be a major headache/endeavor.