Think about three big aspects
- growth speed, which coral can be evasive and just outgrow others. Isolate fast growers
- think about light and flow requirements. Stuff like acros need more of both , while mushrooms need less of both. Not only think your current rockscape, but also how it will play out as the corals grow, they will shadow things beneath them . Type of light (pendant or bar) makes a impact
- think about aggression . Some corals (zoa) can be stayed together while others (chalices, encrusting montipora ) will take overs others. Some has sweeper tentacle and the flow direction in the tank will make a huge impact
Now think about your rockscape, light and flow setup (now and the once’s you’ll change in time ) and then imagine putting different corals in different place and simulate growing them out , u’ll see things fighting , shading or unused spaces in future, avoid those

. Sometime it means changing positions /locations of corals , sometime it means readjusting rockscape or flow while sometime it means just cant certain coral with given situation.
It will be lot easier to have specific , a given tank setup , with rockscape flow , desired corals etc and have specific discussion around it to illustrate this