Far more harder than I think? Where does the 'think' come in? This thing has never been a threat to me, and it was junk while i tested it. While Kyumeru did barely anything, Kuri spread paralysis around while scouting with dragon tail and not being burdened by the worst defensive type in the game.
You also missed the key point: every set it can run is completely outclassed by another dragon. There is never a reason to use Kyumeru unless you're playing favorites. It's even outclassed as a steel lure. Kyu and Zone share a fighting weakness.
Let us take a look at this, then. Just humour me.
Kyuremu has 95 base speed. This outspeeds 538 of 663 Pokémon, forms included. It also outspeeds all other dragons except Rayquaza, which it ties with; Salamence and Palkia, who have base 100, and Garchomp, who has base 102. Of these, Palkia is the best at running a special set, with a massive 150 SpA, while Rayquaza is typically best with a Physical set, with 150 Atk.
I may have missed something, but it appears that Kyuremu has the highest base HP of any Dragon, good Defenses, and a workable movepool. Yes, there are Dragons with higher Attack. There are dragons with higher SpA. However, assuming that Zekrom and Rayquaza are banished to Uber this generation and Kyuremu is not, the only dragons with a higher offensive stat are Dragonite with 134 Atk, Salamence with 135, and Ononokusu with 147. And none of these have an amazing base 130 SpA; in fact, running a special Ononokusu is probably the worst possible option.
Oh no, Kyuremu is priority weak! This may be news to you, but Dragonite and Salamence are also priority weak - in particular a x4 weakness to Ice Shard. I think I'd rather trade a x4 weakness to one of the most common types in the game for a x2 to another common type and a x2 to Steel.
With it's base 130 SpA, it can easily run HP [Fire] to get rid of Scizor, while Bullet Punch will fail to OHKO, ever. Unless you're running min/min 0IV Hasty defenses and it crits or something. Frozen World can cripple switch-ins by dropping their speed a stage, and at base 65 power it is workable. You are still likely better off with Ice Beam, but a stab move that always lowers speed is something no other dragon has.
A lack of Sleep Talk does admittedly hurt it defensively without access to Roost. However, saying something is bulky is not saying that walling with it is the best option. You
can run it defensively, but at least in that regard it is outclassed by Dragonite. Though I suppose Kyuremu, being neutral to Ice, would be better defensively on the special side.
You seem to be suffering from the same issues as the people who dismiss Ononokusu as overhyped have: You are running it
wrong. Kyuremu isn't a wall or support Pokémon, it is a revenge killer that can continue to do things after it has revenged. Forget Dragon Pulse, run Draco Meteor in that slot. It was the same problem with Ononokusu, people were leading with a late-game sweeper and complaining that it wasn't working. It's like trying to run a Curse set on Venusaur, it can, but there are many, many better options to use Curse.
Stop looking at what other Dragons can do better than Kyuremu, and look at what Kyuremu does best.