True mixed builds are hard to use competitively, not to say mixed mons are bad, a lot can in fact be good (and they especially shine on close sheet games where the element of surprise of not knowing if the iron valiant or lucario etc... will click a physical or special move), although they suffer from having most of their BST wasted where more specialized mons with the same bst might have higher bulk or speed or dedicated offensive stat. For more special attack it is also worse as both confusion self damage and enemy clicking foul play would use their high physical attack against them.
Some special mons can manage to fight against dedicated special walls with moves such as psychock, the signature move of Mewtwo and Keldeo or body press, but physical mons are often vulnerable due to burn halving their offensive potential unless you can abuse guts facade, there's also intimidate and parting shot, there are counterplays but not everyone has scrappy or defiant or clear body, snarl exist but with frostbite left in legend of arceus physical mons might have a reason to use a special move to break into physical walls and deal damage to kill specific meta pick targets.
Then there's the "move that can't be abused unless you have contrary or plan on switching out/u turn". It has lots of issues, can't use a choice item, you end up with relying on 3 slot moves, often less in double battles where you often need protect, considering you might also run recover, a status move or a way to setup plus a stab or coverage move it is quite limited, in single it works better at least but it's not the most efficient way to build your mom.
But damn it's satisfying, your 130 physical attacker with a 110 non invested overheat/draco meteor can still deal decent damage, it's really satisfying. If we had more moves of different types like that it might be used more, or an alternative for special mons cause superpower also lowers your defence, imagine a physical move that tired out and decreased your physical attack by 2 stages, could be useful for special mons too, or an electric variant for the mixed electric attackers to justify their 95 special attack cause they either use super slam cell, wild charge, forget their stab options or are forced to be run special. Overheat and lead storm also have the advantages of being booated by sun/grassy terrain, a water or electric move in a meta game with terrain and weather wars might be strong enough to deal gold damage even with an uninvested mon, and they'll become even more common if they add the paradox mons or the tapus or miraidon/koraidon, a water or electric or psychic variant could be nice.
