BROKO THE LOCO STALL
Koko as a stall slot solves a lot of headaches that other stalls sort of have to accept are situations where they have to "just outplay" it.
The idea and game plan remains the same and all the sets are what you've expected from the regular stall slots (Keep rocks off as much as possible with Corviknight, remove items with Toxapex, ruin weathers' day by statusing all their setters, ruin trick attempts with sticky hold Gastrodon) but Koko allows you to slot some of the more greedy options as far as stall goes with its' pivoting capabilities.
For one thing Koko has one of the fastest statuses in the game which lets it act as a suicidal entry/last resort versus some of stalls worst match ups, this being Tapu Lele, Stored Power sweepers and Bandtar sand.
For a second boon it entirely resets terrain which lets it status and "look" for some of the more annoying stall solutions: Koko often scouts scarf/Specs lele and forces out Fini in the early-mid game due to the threat a potential Thunderbolt brings.
For a third boon it has a fantastic speed tier: Outpacing Weavile and modest Dragapult is no joke and threatening kills on most fairy weak threats in the metagame is incredibly appreciated on Stall. This incredible speed tier also lets it turn the tables on some archetypes like Torn T + Slowbro pivot-based offense by statusing the regenerators then turning their attempts to pivot against the stall team with volt switch.
Another thing Koko lets you do as a stall player is to run something most offenses loathe dealing with, A pex with scald and actual items. Pex on most stalls often has to go Shed Shell to offset the weakness and propensity it has to be bullied out of the game by Heatran which often hampers both the longevity and aggressive threat Toxapex can do into a lot of offenses, but since Koko scares out so many knock off attempts in the tier this lets you get away with Toxapexes that actually get to engage in the game past its' function as a Light screen and knock off utility bot.
Here Pex is a scald LS knock off recover black sludge set to really bolster its' match up versus Lele + breakers while being a secondary way of trolling trick attempts but could very well be Rocky helmet haze scald knock recover depending on how confident you are playing into the potential Heatran + Lele match up. With the added Scald from Gastrodon you are looking at twice the potential to scald fish which helps with match ups like Bandtar and Lele and makes them scared to switch in Haphazardly.
The team is as per usual of stall not free of faults: If the opponent remembers how Koko stalls usually play into most wallbreakers they'll just aim to avoid status at all costs and force you into stupid situations like staying in and heal belling with Clefable on something clefable dosen't want to heal bell on at all (Gking being noteworthy). Another issue a team like this faces is its' horrendous match up into the potential Grass spam offense: If that Rilla or Kartana comes in on a good turn where Corviknight is at a low percentage and you didn't get a chance to scald fish them with the two waters or status the Rilla with Koko and Blissey you are in for an absolutely horrendous time.
There's more examples where Koko has shown up on stall but this is meant to showcase more why it has a niche from a stall spammers' perspective, the mon is very neat when used as a stall slot over things like Torn T and Zapdos.