The truth is I have seen Brain coral place along side with scoly and cynarnia. Nothing was wrong, nobody was harming no body. Different species doing fine with each other. I have had a wall hammerthat stings another branching hammer coral, and stinging another wall frogspawn. Same Species hurting the same species. I also have corals that are suppose to have 6+ inches stinging tectacles, which in my tank never stick out more than 1/4 inch. And a mushroom with no stinging tectacles melting away a colony of acans.
The truth is, your brain coral may do fine with the scoly next to it. But is this a risk you want to take?