General rule of thumb... do not mix species. CAN you? If habitats are identical and there are no pathogens being introduced that an animal is generally never exposed to... and you have ROOM... you can. I have co-workers I can tolerate, but I don't want them up my butt (ie in my personal space).
You have a "pair" of young cresteds.... know the gender? If they are a true pair, they too should be separated lest you start breeding when the female is underage / weight.
The animals you're asking about just happen to be something I've had long-term experience mixing. It takes a great deal of time, planning, and observing to do it right.
I realize this is an old thread, but I'll comment for the sake of future "googlers" and etc.
It's not recommended to keep different species together, and especially amphibians together with Rhacs. In fact, you shouldn't keep enclosures containing amphibians close to your Rhac enclosures either, and make sure to keep supplies such as tongs, etc separate. Amphibians are more likely to carry parasites such as Entamoeba invadens without harm to themselves, but it can spread to other species through cross-contamination. This is a nasty parasite that is often fatal in crested geckos particularly.
For that reason alone, don't house them together.
3.7.0 Rhacodactylus ciliatus [Crested Gecko]
0.1.0 Rhacodactylus auriculatus [Gargoyle Gecko]
1.1.0 Eublepharis macularius [Leopard Gecko]
1.0.0 Hemitheconyx caudicinctus [African Fat Tailed Gecko]
I would like to add that the entamoeba virus is associated with frogs and can be transmitted to the geckos. This is fatal to geckos maybe not frogs. So, medicine for this is added to some geckos diet.
I have both a Dumpy Tree Frog and a Crestie. As everyone else has said that is a bad idea on many levels. White's Tree Frogs (Dumpies) will Try and fit anything that moves inside their mouth... including your gecko! They are known to eat rats at adult age. I have had mine for over 12 years and learned that lesson the hard way being young and not researched it. He ate all my other frogs I had in the tank - and they weren't even that much smaller!