Porites can be quite aggressive especially to a monti. Based on my experience, monti generally lose to acropora, leptoseris, stylophora (those have mini sweepers) and recently I found out porites as well. However, monti makes up for it for being extremely resilient and fast growing. My porites that isnt even touching my monti has been stinging it to recession but the sting isnt potent enough to cause a major recession so its very localised. Which means porites and perhaps some sps can be used as guardian corals, keeping certain corals in check. Like what I use my stylophoras in keeping my palythoas in check.