Inner Focus may seem like a pointless ability to have, but it's actually rather handy against Fake Out users, since even if you get hit by Fake Out, Inner Focus protects your Pokemon from flinching, and it can still initiate its move. And of course, there's also the moves that have a chance to cause flinching.
It may also depend on how fast the opponents are. It seems that Oranguru moved before Alolan Marowak and Mudsdale, so it probably isn't anywhere near as slow as Reuniclus. I would predict somewhere around a base 55 speed for Oranguru, but I also speculated that Alolan Marowak's base speed would be 65, but that probably seems doubtful now.
Also, Alolan Marowak did survive Surf during a double battle, so its special defense would have to be better than 50, assuming that Wishiwashi's School Form has roughly the same base special attack as Mega Slowbro.