Mixing amphibians species is very complicated once you take everything the other members here have posted into consideration.

Imo the best amphibian mixes are the ones that have completely different lives. Like borrowers and tree frogs. Or nocturnal and diurnal. If you are really interested in housing different species together than I suggest you do much more research on the species that are recommended or the species that you consider. Continue to do your research and you will not have to ask us anymore . It will be more of a common sense on which species even seem compatible to mix.

My suggestion, Reed Frogs and Dendros or mantella. Again this is not a suggestion to mix the them. This is a suggestion to do your research on them.