Since this is now a permanent ladder I might as well make a serious case to unban Keldeo.
1) It doesn't have a usable native ability, so it relies entirely on its AAA ability to function. This alone is not a reason to unban it but it already shows that it is kinda overshadowed in its role by the likes of Greninja (both normal and Battle Bond).
2)

It's pretty bad into alomst every native Regenerator, it needs to hit Specs Primordial Sea Hydro against most of them to make a dent, and then since it's choice locked they can just pivot out. It's also bad against several common AAA Regenerators like Primarina and Hatterene
3)

It's even worse against Water Absorb mons, native ones in particular already beat it pretty badly and then you can potentially slap Water Absorb on anything to make a workable Keldeo check out of thin air, like Water Absorb Great Tusk
4) Desolate Land also works similarly but it is less reliable against Primordial Sea specifically.
5) Keldeo is also really vulnerable to being revenge killed, both by faster mons (some of which like Latios, Desoland Iron Moth or Ogerpon-Wellspring can even afford to hard-switch in sometimes), and by priority like Grassy Glide and Gale Wings Brave Bird.
The main takeaway is that most teams prepare naturally for Keldeo by including basic stuff like a Regenerator core, a Water immunity, Grassy Glide or a Pokémon faster than 108 base.
Since Tinted Lens is now restricted Serperior could also be considered for a unban, but it is not such a clear cut case as Keldeo in my opinion.