>>45646835Due to the way defense scales, having high defense and low hp is better than high hp and alright defense. If both are uninvested, Slaking can take a tiny bit more neutral attacks than Kartana can, but that's a moot point considering Kartana resists half of all the types in the game with a further immunity to another.
>Kartana's movepool is garbageKartana's movepool is excellent. It's a circumstance of the meta that it isn't an absolute terror right now. Getting walled by Zapdos and Moltres isn't that much of an issue, especially since Slaking wouldn't fare all that much better.
And I used Conk as an example because it's a huge stat beatstick that isn't actually all that good in practice. Slaking has serious special bulk problems, like Conkeldurr, with way more, but still unimpressive speed. Base 100 is fine, but it's not winning any awards in 3 tiers where threats regularly exceed base 100 and there are tons of great scarfers. OU, UU, and RU would blaze past Slaking, because holy hell NU is a mess right now.
Slaking has good bulk, alright speed, and alright attack (unboosted), but it would suffer from Mega Garchomp issues. Except Mega Garchomp has even more attack, and better boosting moves (SD), but without an item, its 170 base attack isn't all that impressive ultimately, leading to it being used exclusively as a bunker buster of sorts where it sets up SD and spams STAB EQ. Meanwhile Slaking's best STAB is 85 base power, compared to Garchomp's 100 base power EQ coming off 10 higher base attack.
Slaking, even with klutz, would likely end up a victim of the meta in UU and drop to RU, where it would be a menace. It won't make OU past the first month of new-toy syndrome, and that's a fact.