As an Inkling main, I'll tell you how to beat the roller:
Just hit it. It's priority is abysmal, like the only thing it beats is Blade Beam, which isn't really a good move anyways. Or, just shield. If that happens, either we have to jump-cancel retreat, or get punished because the hitbox doesn't come out again until a couple moments later. Or jump. The roller doesn't work against aerial opponents at all, like, it does no damage in any way, even if Inkling is in the air.
This is why roller is mostly used for hard reads or tech chases. It isn't safe just to throw out like any other attack.