I really don't see the point in threatening Scizor. Most common Sun members either have a fire STAB, or carry a fire coverage move. I may be a bit rusty with sun (BW1), but I distinctly remember having an easy time with Scizor. This pokemon's purpose is to help Sun, giving it a way to beat Scizor would be redundant as Sun doesn't have trouble with Scizor to begin with. Not only that, but letting CAP 5 beat Scizor means it becomes better on weatherless and sand as well. Oh, how the plot thickens! If CAP 5 can beat all of rain single handedly, well, why not use it as your Rain counter on Sand/weatherless (other than one redundant STAB with Tyranitar, though we're going on the assumption that this thing beats Lati@s, so I'm guessing either high speed or SP, which combined with a Grass STAB that would differentiate it from Tyran)? This thing needs to be reliant on Sun somehow, and I see no better reason than Scizor weak.
Also, if you can't tell from the above, I firmly believe we should be able to threaten Politoed, and the Lati@s. Keldeo? I'm iffy. It wasn't around when I played sun. I know that I despise it when I play weatherless (or Tyran disrupter weatherless). I'm of the opinion that CAP 5 should, under no circumstances, give Keldeo any switch ins. However, we also shouldn't be able to stop one that's already. Most sun teams have Ninetails, along with Volc and/or Venu. If used along Venu, a fighting move would let Venu come in and force Keldeo out. If they go for an HP Ice to hit both CAP and Venu, they risk giving Ninetails (or the less risky for sun player Volc) a switch in to bring back sun. While this means the Sun players needs to predict to win, which is risky, it's not like its an unwinable scenario.
For steel types. Heatran yes, Ferro and Skarm no.