It's a tad harder than that. "Common" softlocks generally put you in the elite 4 rooms, with 1 pokemon that is underleveled and knows splash, with all others released. These elite 4 rooms are generally the only rooms that you can enter but not leave (except by beating the trainer or losing), and then you create additionnal constraint to prevent a combat loss from freeing you, like purposefully not picking up a lot of optional items that would make it easier to bounce back.