Pilo: Ban

Three main reasons

1. Defensive counterplay is virtually non-existent in this tier, especially with the departure of gurdurr.

There are two pokemon in the tier which resist pilos stab combo in bronzor and dewpider, neither of which are particularly viable and fitting them on a team solely for pilo would be using pretty unviable pokes for the sake of checking pilo. Dewp also still needs to be max max to make banded eq a 4hko.

Defensive checks are also limited to clef (if not banded), dusclops (4hko if evio, 3hko if band), prinplup/wartortle (4hko no band, 3hko with), ferro (4hko if evio, 3 if band), machoke (cannot switch in if band, 3hko evio), slowpoke (3hko if band, 4hko if evio) and marshtomp (3hko band, 4hko evio)
All calcs were done assuming all mons were max hp max def +def nature invested barring machoke, which was ada max hp.
Admittedly, the list is larger than with gurdurr but a similar question arises with pilo too in what do you do back once you switch in the defensive mon? Clef dies to band, or spams softboiled and prays for no flinch/miss, dusclops clicks rest, wisp or night shade, not threatening for any playstyle barring ho, the waters click an extremely weak scald, defog/spin or toxic if there's no poison on opposing team. Only ferro/machoke offer some degree of offensive pressure or long term annoyance with knock/hazards to any team. Only two pokemon on that list have reliable recovery; clef is the shakiest check to pilo since it's forced to recover and can be flinch spammed down since it does very little back to pilo (Moonblast is 4hko if band, not even a 5hko if evio) and poke is better but is more a specific pilo check, it does not offer much in non-pilo games, far harder to put on a team and even with pilo there, it bleeds momentum and has to be careful of any hazardstack, knock or toxic.

On top of this, pilo (especially band) can/should run enough speed to outspeed everything above, which means all those calcs turn into one time switchins at best. On top of that, nothing there barring choke can ohko band in return.
All the above also assumes you use these defensive mons solely to check pilo which is not the case in a normal game. The waters check monf, steels, krok and more, clef checks scarf monf, weak defensive pokemon with no setup, kad etc. All the defensive pokes above can easily be pressured by teammates or by pilo to open up the team for each other.

2. Piloswine has incredible bulk for this tier, while still having a solid offensive presence.

Every defensive pokemon listed above barring choke is forced to run max max or some fully defensive spread in order to be a good defensive mon. None can afford the evs to invest in phys attack/spa while being good defensive pokemon. Piloswine is so bulky with evio that it can afford to run max ada attack and hp and can even take some hp evs out in order to speed creep certain mons. Even stab super effective attacks from invested pokemon fail to ohko this behemoth (ada max machoke cc does 71-84%, monf fb does 70-80ish%) so even though the ice typing is awful defensively, the sheer bulk of evio pilo makes up for that.
Even band is reasonably bulky considering its purpose is to be an offensive beast, and nothing barring strong se attacks can outright kill it, so again either set can easily take a few mons down with it.

3. Pilo has good versatility and is a threat vs every playstyle

Both band and evio rocks pilo are very splashable and easy to fit on any team. Band eq/ice stab rips through defensive cores and builds, while banded ice shard is very dangerous to ho builds, since it outright kos lo kad, does 72-85% to haunter, over half to ebuzz etc). Evio rocks is difficult to kill without taking major damage yourself.
Pilo also has the less used but still semi viable curse and amnesia sets. The first is a solid wincon/breaker capable of eating hits on the physical side and dealing massive damage, while the second takes advantage of would be checks like clef and the waters and sets up on them.

Overall, I think pilo is too good for the tier, puts a massive strain on teambuilding and is a massive threat before and during games.