I would like to make a water cube however I would only one plane/surface to have the water simulation active so the title pretty much sums up what I want, the simulation I would like to have should have water physics/movement on the top plane of the cube while the side plans would follow the movement/physics of the edges of the top plane but have no other physics them self, bottom plan would be a still plane. Thank you for your help.
Ok! Sounds like fun.

Create your cube to set it to be a fluid simulation bound. Fill it with fluid using another cube and gravity should hold the side and bottom faces flat. It may need a few frames at the beginning to settle.

In theory, the simulation should bake and only the top surface has room to move. If there are any inconsistencies, use the boolean modifier to clean up the sides.

If you want the fluid to flow over the edge that is a whole nother step of complexity that I feel you haven't asked for. If this is what you want please update your question using the edit button.

If you are confused about any of the topics I have brought up and are not in italic, I will help you. Any in italics are easily found on the internet so please don't ask.

Not meaning to be rude but no need to repeat what is already freely available :D

Good luck with your project and I hope I helped,

BFB