Ok, while pachirisu being used in a winning championship, everyone needs to understand some things:
SMOGON IS ABOUT SINGLES.
Doubles is a completely different metagame. Many different abilities and moves that are useless in singles (like volt absorb, follow me, wide guard), moves that hit multiple targets, and the ability to pair pokemon with each other. A pokemon could be horrible on it’s own, but amazing with the right pokemon. I IS A VERY DIFFERENT META. YOU CANNOT COMPARE THE TIERS OF SMOGON TO VGC.
Second: Even if you went by tier, THE CHAMPION USED TALONFLAME AND MEGA GYRADOS. THIS WOULD MAKE HIS TEAM OU.
Having a single pokemon of a higher tier makes the team that tier. Thus why you cannot have an uber in OU battles.
Third: PACHIRISU DID NOT KILL THEM. Pachirisu acted as a SUPPORT pokemon. It used super fang against bulky pokemon like zapdos and mega garchomp to make it easier for gyrados and talonflame to sweep.
If you don’t want to follow smogon’s rules, don’t. But don’t be an asshole about people who prefer the rules. The goal of smogon is to create a competitive singles environment where multiple playstyles can be viable and FUN TO PLAY. As well, to create a metagame where luck is as little a factor as they can make it.
It’s not a meta for everyone, and it cannot be applied to doubles except perhaps as a move or stat guide.