I don't see what non-BP Smeargle would accomplish for the tier. It's a very bad lead, yeah it has Spore but Azelf and Custap Forretress(or even shuckle if you want sticky) are miles more reliable. Keep it banned imo, it doesn't do unnecessary rule bending and saves effort that could be put into looking to potentially broken mons.
Smeargle also has Magic Coat which bounces back faster Taunts, which none of those have. That alone coupled with hazards and spore puts Smeargle in a very unique position. It can grab momentum in several ways. That base 75 speed also puts it at a decent speed tier. + Speed nature and 252 Evs is faster than Modest Nidoqueen, Adamant Honchkrow, Modest Mega stoise, Mega Swampy, all the clerics in UU and most hazard setters (forry, donphan, empoleon).