... Being honest...
In an RP there can be powerful NPC's, yes. But the focus in an RP is on the player characters. The player characters are the ones who should be able to solve big problems and defeat major threats.
This actually was pretty well exemplified in this RP, in the actual heroes vs. villains fights, the heroes were able to do quite well and defeat them. But then we get to this training mission. The player characters having a tough time is fine, but this is beyond that. The player characters should be able to actually fight the others. In some cases they're decently-established heroes in their own right, or at least have plenty of experience. If it's basically "the player characters are effectively useless" I really don't see much of a point because this is an RP where the player characters are meant to be the central focus.
RP's aren't supposed to feel like your characters are totally worthless and outclassed. But it's honestly feeling like that with this training mission. It's been dragging on for a long time and nothing any of the players do seems to stick for any significant amount of time. It's honestly a stark contrast between the fights with real villains, where the player characters really did feel like they were the focus.
I don't expect this to be easy, but I don't expect it to be completely impossible either. By now the new(I use that term broadly given that some of them are actually not particularly new to being heroes) heroes should have made some major progress. It would have been tough, but they could have done it.
But now, well... let's look at Hot Rod, Charlotte, and Rolling Girl. Charlotte is a highly experienced magic user with a variety of tricks up her sleeve. I would need to look at Rolling Girl's bio again, but she's a speedster who can probably deliver some pretty hard hits. Hot Rod is the same, given his current speed.
There is no reason they shouldn't be able to take on Sentinel. I'd say even individually they should be able to, though it would naturally be harder. Charlotte has magic and experience, and I imagine super speed would be pretty useful against a telekinetic. That's only one example of how ridiculous this training mission has turned out.
This entire training mission has ceased to be fun long ago, and while I joined with the expectation that there would be NPC heroes more experienced then the players(by varying degrees) I didn't think that meant the players would basically be totally ineffective compared to them.
As for you, Yog, regardless of power level the players are still supposed to be the focus. Some players have few or no powers, being more powerful isn't the issue.
And please don't make disparaging incorrect generalizations about things I enjoy, thank you very much.