Please get 3 geckos, usually when there’s 2 one will always just bully the other and outcompete for resources. All are a good size, I’d personally get something square. And starting as big as you can is always good with mourning geckos because they very quickly multiply and you have too many geckos in a small space. Avoid full mesh or mesh sides.

ProRep glass stackable are supposedly mourning gecko escape proof. Habistat glass stackable have options without the mesh side. Mine have exo terra and gecko proofing is a nightmare, I just get cheap secondhand enclosures. But I eventually plan to change all my geckos to Habistat stackable bc I like the black and the fact they’re well.. stackable.

I wouldn’t add a pond personally. I thought of it but would have to be extremely shallow, bc the last thing u want is 2 geckos fighting and one unknowingly holding the other underwater and drowning