You tend to see a few viable sets:
- Boots with Beam / Freeze Dry / Earth Power / Draco Meteor or Scale Shot (you can occasionally see Rock Slide or Substitute, but neither is a need and it is hardly strapped for slots since it has coverage for the entire tier)
- Specs with Beam / Freeze Dry / Earth Power / Draco Meteor (you rarely see Blizzard when paired with GKing Chilly Reception, but definitely not strapped for options
- DD with DD / Icicle Spear / Scale Shot / Tera Blast (with options for Fire, Electric, and Ground even)
When you combine every single set, you have too many moves, but each individual set is pretty well-covered within 4 moves. I do not mean to beat a dead horse, but I think you have a misunderstanding of what "4mss" is because if we use this thinking, then any Pokemon with multiple movesets suddenly has it -- and that's not how it works.
Kyurem is a good Tera user, but no set is too dependent upon it -- DD is the least common variant and the most Tera dependent for sure, but even then it is not drastic enough to be a major cost factor and burden on the team itself.
Let me give you both sets that I used today, and MAYBE you'll see where I am coming from (or just y'know, drag my ass through the dirt still.)
Kyurem @ Heavy-Duty Boots
Timid Nature | Tera Ground
252 SpAtk / 252 Speed / 4 Def
Ice Beam
Freeze-Dry
Draco Meteor
Earth Power
Kyurem @ Loaded Dice
Jolly Nature | Tera Fire
252 Atk / 252 Speed / 4 Def
Icicle Spear
Scale Shot
Tera Blast
Dragon Dance
First set was ran on a Webs oriented team. It generally outperformed the DD Dice set, but still had issues against Boots/Flying/Levitate users. The lower speed was always a problem, unless coming in on something that took the Webs reduction or was naturally slower than itself.
Second set was on a more standard "balance" team style that I use. It could handle MAYBE one a half mons, but if the opponent had ANY kind of setup mon, Kyurem was either totally deadweight or entirely reliant on its Unaware partner -- which didn't always work out well. I committed Tera on this set far more often than the Boots set, just to TRY and get a DD off.
Sure, having both Ice Beam and Freeze-Dry on a set is not the best of forms, but the additional damage on an obvious resisted switch is worth it. But if you really want to argue having both is bad, then look at the list of other Special Attacks Kyurem gets and tell me which one fits best. Please, I'll wait.
I found Kyurem to be mid at best for me. Very difficult to get in safely, scared of hazards, scared of many threats in and out of the tier.