Some mons are not suspected because of how "good" they are, but rather what they can do at their heights. Kyurem is one such case where it could run a lot of sets that required somewhat different play patterns to beat, but many of said sets required massive amount of support between adequate hazard removal like Great Tusk (which has defensive synergy issues with Kyurem), slow pivot support, and a proper defensive backbone - and even then Kyurem can end up falling short if it isn't correctly played. Sure Subtect Kyurem might seem broken when you get that match-up into Garganacl and keep Entry hazards off, but then you struggle to remove entry hazards in other match-ups as you will in SV, and end up losing 1v1 to random mons like Moltres or a fully setup Zamazenta that Kyurem itself will have very little practical utility against. I'm sure many players who voted in the last test (particularly on the dnb side) would agree that Pokémon like Darkrai, Ogerpon-W, and Gliscor are easier to slot onto a team while also proving to be more and more consistently useful on a game to game basis due to their innate traits like higher speed, better defensive utility, etc. The vote was close but I feel Kyurem was banned for being able to carry to many hats that required mildly different play patterns to check rather than being stupidly excellent or easy to use in any given role like the aforementioned Pokemon. That isn't to say it was "bad" at a lot of its roles but it wasn't the top of its class at most of them.
Hydrappl being better is a joke but I did see a few teams like the blimax one sub out Kyurem for it and it did have a lot of its own perks like forming double/ triple regen cores with Mola / Gking, more opportunities to switch into threats because no rocks weakness + Regen (although it's bulk is a bit suspect without investment), and a better natural MU into a few threats like Garg.
As for Fickle Beam, the proc rate being 25% higher than crits is a big reason as to why I can find it somewhat "uncompetitive". These are also pre-gen 6 crits so they are hurting a lot more. It would be a lot bigger of an issue if Hydrappl didn't need to setup beforehand to be threatening, but there have been many cases where I just rolled the dice with Fickle vs one of apple's counters and been rewarded with a KO.
