Hi again, I do not know if I'm on the right forum but I try: there is in Little Cup a list of pokémons banished quite consistent (I do not dispute at all their power), but some of them deserve an explanation
* we understand that Vulpix was ban for Drought: why not forbid this ability since it is the only one to have in LC? Is this a sacrifice for the example (I doubt that Vulpix with Flash Fire outclasses Ponyta)?
* ditto for Meditite, who is an eternal banished: why on Earth do not ban instead Pure Power (where he is still the only LC to know)? It isn't nonetheless unusable: it has a unique double-type in addition to an interesting coverage.
* it's more complicated for Porygon. I guess Z-Conversion is the thing that set fire to the powder (but the pokemon is already extremely cumbersome in itself: it would have been suspect-test anyway). It seems to me that it was not envisaged to first prohibit this move, then to check the influence of Porygon LC if it is still broken.
I understand the argument to avoid complex banns but the examples cited are absolutely not. Take the example of the Middle Cup in 6G: Combusken is ban for Speed Boost (but Whirlipede is not broken); Protean (Frogadier) and Contrary (Servine) are forbidden abilities because a single pokemon learns it in this format
Ultimately, it comes down to what the banning philosophy is, and the general way that Little Cup bans things is that we do not ban parts of a Pokemon to nerf them down to usable levels unless the factor itself is inherently broken/uncompetitive, and that it is preferable to ban a Pokemon.
Vulpix is the only case of those three where you could make an argument that Drought itself was the broken factor, but ultimately the decision was that Vulpix itself was the broken element since for all intents and purposes Vulpix
was Sun.
For Meditite, Pure Power is a renamed Huge Power. The ability Huge Power is not inherently broken - this is clear to see by Bunnelby and Azurill's lack of brokenness. Banning Pure Power would simply be a nerf to Meditite in order to keep it despite Pure Power only being broken due to Meditite's unique traits including its typing, stats, and movepool.
Same deal for Porygon - Z-Conversion is simply a part of the Pokemon. If Porygon didn't have Download, the high stats, and fantastic movepool it does then there's every chance that Z-Conversion sets wouldn't have been broken. You're absolutely mistaken that there wasn't debate as to what to ban in the case of Porygon, there are pages of discussion about exactly what you propose, however adding to a Z-Conversion ban would be how to implement it. Should we ban the unbroken base move Conversion? Ban potentially unbroken sets by creating a complex ban of Porygon holding Normalium Z and the move Conversion? Create an in battle mod where the move Z-Conversion could not be selected? Ultimately the clearest decision and the one made by the council was simply to ban Porygon.
It doesn't really matter what other formats do for their banning, especially when said format isn't an official metagame, so what Middle Cup did has no bearing on what Little Cup tiering should be.
Thanks for the question!