WAREWOLVES---- Are pureblood warewolves আরো powerful than muggle-born and half-blood(Remus) one? Can they transform at their own will?

I don't think the blood status affects the magnitude of the wolf's power. Fanfics are fanon, so pretty much everything written in every one of them is going to be inaccurate.

I DON'T THINK SO?

Lycanthropy isn't a blessing অথবা a power it's a curse, আপনি don't control it so no, আপনি cannot transform at will. Nor can আপনি stop yourself from being transformed at the full moon unless আপনি take wolf-bane (which is complicated to make, and in which case আপনি aren't a werewolf but a normal wolf).

The blood status shouldn't have anything to do about the transformation. It doesn't prevent being bitten so I'm pretty sure it doesn't help আপনি out later on.

Fenrir Greyback was either pureblood অথবা half. Either way he probably told Voldemort he was pure, like most death eaters do.

And fanfictions aren't fact, they're just the writer's imagination going wild.