Hey! Need Your advice

Hey! thank u for reading this. My boyfriend is just now getting into reptiles because ive had several. He has this idea that he wants to get this really big aquarium and have a water side and a land side. He wants to put different reptiles in it...frogs,hermit crabs,lizards. Since ive had lizards I know putting all those things together proabably isnt possible lol. I wanted to know though is there ANY reptile that can be housed with a different kind . Ive seen water dragons,frogs, and chamelians together. That was at a petstore so I didnt want to go off that..knowing pet stores usually do the complete wrong things where I live. Also wondering if you can put hermit crabs in a aquarium with other lizards? on the water side of the tank my boyfriend wants to put some small fish in there. I used to know someone with a water dragon who had a land and water side and it worked very well. I just wanted to get ur opinion on all of this! any advice would be really appreciated and if you house ur lizards with other lizards id love to know about ur experience. Thanks !