One of the most intriguing changes done by a few Pokemon fangame mods is a complete rework to the Stall ability, and it's...certainly an interesting one. Instead of its current useless detrimental effect, the pokemon with its ability now quite literally stalls for time instead, forcefully causing an empty turn in the battle, every other turn (this stacks in double battles/if multiple mons with the ability are present on the field). During this empty turn, no combatants may take any action; the only things that occur are end-of-turn effects.
While this seems pretty simple at first, the ramifications only become more and more terrifying the more you think about it; it's a free turn of leftovers/poison heal/leech seed etc recovery, an additional turn of passive damage from weather, leech seed, status, etc, an additional turn in which the toxic damage counter increases, an additional turn that decreases the duration of field effects (weather, terrain, trick room, tailwind etc) as well as other detrimental moves (taunt, encore, disable etc), and even essentially allows wish recovery to be applied at once/future sight to land at the end of the next turn, and hell, it even skips hyper beam's recharge turn, and even truant's useless turn (it does NOT do anything about confusion/sleep/freeze/gigaton hammer though, as the pokemon needs to take an action to decrease their counter). And there's nothing ANY pokemon on the field can do about this; the empty turn is applied every other turn, which can make the presence of passive sources of damage that you'd normally shrug off for like, 2-3 more turns a significantly more daunting prospect to weather.
....Makes you glad the ability's only stuck on one mon all of a sudden, huh? After all, it would be very easy for a mon with the right tools to break this ability completely, especially in tandem with protect....One could even argue that it would still be insane even if the ability still had its old detrimental effect....