Of the 3 new Unaware users in Gen IX, Clodsire is the weakest, but still has strong points that have it stand out. Unlike Skeledirge, Dondozo and the available Quagsire Classic, Clodsire has phenomenal Special Bulk as opposed to the other's physical. Furthermore, it is the first Ground Poison type since Red and Blue (Nidoking and Nidoqueen) and can fully show off the type's defensive merits... Sadly Ground and Poison have many predominantly physical resistances (bar Poison, Electric and Fairy) and special weaknesses which seems to be a mismatch but the areas where Clodsire shines, it really shines.
Clodsire easily sits on Iron Moth, Nasty Plot Gholdengo, Volcarona and H-Zoroark with ease thanks to its insane special bulk. While Skeledirge and Dondozo can cover some of these, by dint of their paltry Special Defense and in some cases typing, they can't cover all these threats the way Clodsire can. Additionally, both are ruined by Toxic Spikes (well ok, Dondozo can wipe that with Rest, but that represents its own problems), while Clodsire can wipe them away and even set them up by dint of its Poison typing. Clodsire walling these threats so effortlessly gives extra value to its own Toxic Spikes and other entry hazards, which thanks to Unaware + Recover, Clodsire has the bulk to repeatedly throw up these hazards in the face of removal.
Clodsire is not without competition however. In addition to the aforementioned Unaware users there is Ting-Lu. While lacking Unaware and its Toxic Spikes immunity, Ting-Lu makes up for it in spades with absurd bulk both physically and specially, enabling it to take hits Clodsire can only dream of. Yet Its lack of recovery means that Clodsire shines more over protracted battles, as Ting-Lu can be worn down, but Clodsire takes so much more work.
Water Absorb does deserve mention. In addition to completely stymieing Walking Wake with Tera Fairy, Water Absorb turns Rotom-Wash into almost free setup (Clodsire does not like getting burned by Will-o-Wisp), as well as Dondozo, Pelipper, Gastrodon, and Toxapex who all regularly lack the coverage to deal with Clodsire.
Clodsire excels on bulkier teams that can play out the long game and draw extra turns of Toxic damage. As such partners like Dondozo and Corviknight stand out for being able to stall out precious turns and being physical walls who compliment Clodsire's special while enjoying the Electric immunity it provides (and able to answer Ground [both], Ice [both], and Psychic [Corviknight] attacks. Gholdengo deserves mention as well -keeping Clodsire's hazards up makes a world of difference in winning the chip war.