Hairy Gregory: See below
Raskolian Phoenix: See below
Ok this is the main bits in a nutshell, it should be in more detail next chapter.
The person is pre-powerpuff. The Professor was part of another team of scientists then and created a more powerful version of the Powerpuffs with a refined version of chemical x. Unfortunately, back then he didn't have the experience to create a specifically good person. As soon as she was born she destroyed the lab as well as herself and the Professor escaped. If you noted some of the finer points e.g the time 1:23 you'd notice it was Chernobyl where it happened. Well the Professor, back then didn't want to ruin his own career and kept it a secret from the other members of his team of scientists and simply faded from history. Now one of the older scientists recreated her. This chapter just strengthens the fact the physically she is stronger than the girls. I don't want to put too much info here so that should be enough to tell you a bit of the plot.
Buttercup shivered and glared angrily at the glistening drops of water making their passage down the gilded logo. She shook the rain from her back. It just had to rain when she was on stake-out doesn't it. She cursed her ill-luck once more and tried to find a comfortable bit of rock to lie on which was surprisingly difficult seeing as all the available niches and crevasses had rapidly filled with water and the dry bits seemed to be just too small to fit her size. After a few more moments of slipping around on the awkward roof she resolved to return home. Besides what villain would rob a bank in weather like this. As she slipped into a very muddy puddle she lost control of her temper and shouted vehemently into the uncaring sky.
"Come on! You can rob this stupid bank for all I care!"
She turned her head in disgust as the sky, obviously gave no answer. She spat the mud that had filled her mouth aside and prepared to fly away when the spit laden mud ball flew back into her face. She spun around to face her antagonist. She was a tall woman wearing a robotic metallic-green suit. What struck her were her physical characteristics. She wasn't particularly deformed, oh no, she wasn't even monstrous. Not even a fuzzy kinda-cute monstrous like Fuzzy Lumpkins. In fact she looked exactly like her. Same aspheric head, massive eyes. Same fingerless hands. In fact she was the splitting image, albeit an older one of her or any of her sisters. She smiled benevolently at her, gazing at her with cold eyes that twinkled with icy humour.
"Yes, I believe I shall take the money"
Buttercup regained her composure, and, like she always did, threw herself into battle. She jumped into a simple running attack at her armour clad antagonist, giving her a full punch to the face. She continued her relentless concession of blows until she began to tire. With a final parting kick she floated up to survey her handwork from aloft. Then she was surprised when her enemy swung a fist at with graceful, almost mocking ease, dealing her a surprisingly strong blow. She was sent spiralling into the bank. Wiping away the blood from her eye, Buttercup quickly got back onto her feet then stopped in shock and stared at her hand. She was bleeding! With a roar she dismissed the blood and flew for the door. Oh, she was gonna pay! She was going to pound her face into pulp!
Buttercup darted out of the door and gave a loud guttural cry as she flung her fist at her enemy. Or, to be precise where her enemy used to be. With a feint she dodged to the left and gave her a vicious kick followed by another applied to the front of her face. She gave a cry of pain and grabbed her face, twisting around in agony. She heard her speak into her ear.
"Too slow little girl"
Blinking away the pain she tried again, vainly to connect her fist with her enemy. With a final smashing blow she managed to knock her fist into her back. With a satisfying crunch Buttercup heard her enemy's armour crack. Her foe snarled at her and grabbed her dress, bringing her to her face so Buttercup could feel her hot breaths steaming on her face.
"You don't want to make me mad"
With a short laugh Buttercup head-butted her in the face. With a snarl of frustration her enemy flung back at the bank, the ungiving wall crushing the breath from her chest. Her enemy flew over towards her and mockingly stepped over her into the vault with her crash had cracked open. She laughed down at her as she picked up a single dime.
"Just needed some spare change"
Blossom flew down to the front door and shook herself to get rid of the excess water. Then she stopped in shock. On the floor sprawled the Professor Looking up. He was muttering incoherently in his sleep. Must warn the others, I should have known un-warned they could recreate her. Blossom slowly lifted him up and carried him up to his room.