Following Zacian-Crowned's ban in January, Zacian-Hero has seemlessly stepped into the vacancy left by its big brother and it hasn't looked back since. Like Zacian-Crowned, Zacian-Hero has Intrepid Sword as its ability, which means it too comes out of its Poke Ball with +1 Attack ready to go. While Zacian-Hero isn't as well rounded of a Pokemon as its sword wielding counterpart, it is every bit as powerful and more. It may not appear that way at first, as Zacian-Hero only has a base 130 Attack stat, as opposed to Zacian-Crowned's ridiculous base 170, but unlike Zacian-Crowned, Zacian-Hero can actually hold an item. To give you an idea of the significance of that, here are a few damage calcs to help paint a better picture
Essentially nothing available to us is safe from Zacian-Hero's onslaught if it uses a boosting item like Choice Band. Because of this, Zacian-Hero contantly forces 50/50s and can straight up end the game if you get it wrong even once. On top of that, Zacian-Hero is an incredibly potent user of Swords Dance. Without having to hold a Choice Band, it can handily bypass counters like Necrozma-Dusk-Mane through a Babiri Berry, for example, as well as taking advantage of Pokemon like Ho-Oh or Eternatus trying to pivot in on a resisted move from the Choice Band set. To make matters worse, Zacian-Hero has an astounding base 138 Speed stat, making it difficult to check it offensively as well. This incredible offensive pressure has lead to Zacian-Hero putting a huge strain on both team building and playing in SS Ubers. Since not even the best physically defensive Pokemon are enough to withstand Zacian-Hero, we now often see teams that stack a combination of shaky answers like Necrozma-Dusk-Mane, Ho-Oh and Tangrowth together on a single team
It isn't all sunshine and rainbows for Zacian-Hero, though. Where Zacian-Crowned was part Steel-type and content absorbing Knock Off, Zacian-Hero is a pure Fairy-type highly reliant on its item, regardless of its set. It can't switch into any of the top tier SS Ubers Pokemon reliably and is very prone to entry hazards, too. On top of that, Zacian-Hero has to battle through Rocky Helmet, if not multiple helmets, to make progress, resulting in it being worn down rapidly in many of its games. Even so, Zacian-Hero's stronghold on the metagame has motivated the Ubers Council to suspect test it. We're looking forward to your posts on the matter, as well as your participation in the voting process. Please read through all the information and rules outlined below before getting started
Source: https://www.smogon.com/forums/threads/np-ss-ubers-stage-7-heroes-zacian-hero-banned.3685323/
Also, it is of no significance if a Pokemon is useless in an above tier. Take Cinderace for example. It was banned because with its dumb boots, libero and you turn, it was really difficult to deal with without helmt Slowbro or tank Chomp. However, in uber, Cinderace is complete garbage. It's ranked so low in the viability. I believe it's only D rank. Maybe even lower
With Calyrex, it's because of Yveltal. It may be strong but Yveltal checks it and is a very great Pokemon. Yveltal has been the number one mon in usage because of that for months now, I believe
Finally, just because a Pokemon has higher usage does not exactly dictate if it will be banworthy or not. What makes a mon banworthy is its effect on the metagame regardless of its usage
