[Autumn]

Its not like null shell is being gutted or having its identity removed, you're just moving the effects around so that the actual dispel effect has a drawback, not being able to use shells again for 2 turns, and denying it from being so easily applicable via spark drive, you're definitely blowing this out of the water I think as it isn't that drastic of a change, but one that feels more fair in my honest opinion.

FYI a good portion of the statuses you are listing disappear on basic attacks even landing, such as disengage and miragewalk, so they don't get nulled by null shell unless it were lead storm applying it, an issue for multi-shots specifically on poise I'll give you that, but due to the damage threshold, poise also disappears when a single shot gun hits the target and dispels all of its statuses, so if anything landing an attack dispels 3 more statuses than intended.