A Zoo in my area had four different kinds of Poison Dart Frogs housed in a single terrarium no larger than a 20 gallon long. It seemed questionable to me.
I would never house any kind of a Toad with any other kind of animal due to their toxic secretions, the same goes for many species of Salamander, especially Efts and Fire Salamanders.
I've seen (in very very VERY LARGE vivaria) Green and Brown Anoles, House Geckos, Green and Barking Tree Frogs, as well as Grey Tree Frogs and other small Tree Frogs all housed in the same enclosure. The Enclosure was a living vivarium with lots of space for each creature. The Brown Anoles dwelled near the flooring, the Geckos stuck to the back wall and sides, the Green Anoles basked near the top all while the Tree Frogs slept tucked away during the day. At night the Tree Frogs, all of which were similar in size, would leap around looking for crickets. Each species had its own niche, were all gathered from the same area of Florida, and were of similar size. The Vivarium was alive with plants and living mosses and a pump driven water system.