How powerful is Trundle?
 

According to his lore, his regeneration is monstrously powerful.

Is he individually stronger than any other champion or is he weak because of the curse he sustains?

The curse he sustains eats away at his flesh at nearly the same rate it regenerates.

Yeah, unfortunately his otherwise extremely powerful regeneration is hindered by constantly pushing back the flesh-eating curse. Without the curse, however, I imagine he's basically unkillable, as his lore implies that he can heal mortal wounds in an instant.

I don't have anything to say contributing to trundles power, except possibly to say that we can derive from his moves rather than his lore that he gets some power from his curse in that he uses it to hurt champions.

I actually intended(and you can see my crappy sentence structure up there and here) to just post about how epicly tragic and noble trundle is.

... except for the multitudes of mages that could destroy him instantly, such as brand or xerath

He would be a miniature god if he wasn't cursed.

Remember the scale of this curse. It would have killed a human village in a little more than a day, but the trolls had it for generations, and it was on an entire village of trolls (my guess, around ~250). This means he's the Wolverine of Runetarra, and Wolverine has survived complete disintegration multiple times.