Yeah Scizor is still pretty good, but as UltiMario has informed me, Heatran is now widely used, and unless you're willing to bullet punch a Heatran, it's going to fry you (choice scarf equipped as I recall?). Of course, you could always switch to some UU Flashfire sweeper to take the lava plume or whatever, or if you predict that your opponent is going to predict that you'll switch and has their Heatran use Earth Power instead, Scizor could use Superpower.
As for Slowbro, it's still UU because it's...underused. Obviously, right? I feel outdated, common leads when I played were Aerodactyl, Skarmory, Starmie, Swampert, Crobat, and Jolteon. If only my brother hadn't water-logged my DS...