A lot of Pokemon that are UU and below can be effective if piloted well enough by a decent player. Players like Blimax have been able to make a lot of more niche picks like Arboliva, Bellibolt, etc. on the mid - high ladder, and I have seen a lot of other Pokemon like Lowkix be used on high ladder to ok success. As other users have mentioned, picks like Paldean Tauros and Blissey can still be effective in the tier to check some key Pokemon like Chien-Pao and Scizor. Hell, I've been swept by something as benign as Tera Electric, Leftovers Frosmoth because it could setup on my defensive Pokemon quite easily (Garganacl couldn't break its sub w/ Salt Cure) and other mons like Wish Regen Alolamola have give me a hard time since they trapped and KO'd my great tusk, which wasn't something I expected at the time. Even against mons that I didn't have a hard time beating, there was some interesting tech I spotted like Hawlucha being able to ignore Gholdengo's Good as Gold with Mold Breaker Defog. Generally speaking, lower tiers are used less for a reason, but these mons still can do things that can be fun to play around with and can throw people off-guard given how infrequently they are used compared to staples like Great Tusks, which can make them harder to deal with at times.