probably not a good idea, the possibility of the gecko attacking the newt or frogs is pretty good especially if there is a great size difference in the animals. in addition, crested geckos are not great swimmers and it could drown in the aquatic environment.

in general it is not a good idea to mix species, it greatly complicates things in the terrarium and your animals will probably come into conflict.
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2.2.9 Crested Geckos
0.1 packman frog
1.1.1 Box Turtles
3 green and black auratus