This beautiful babyfur commission by  koleo features not exactly Pokemon, but squrrel-like critters as part of a species called Shifters that are pretty much the pre-cursor to Pokemon. Specifically this is Monarisu from "Flint the Time Detective" and her Super Transformation counterpart, whom I've christened Atoashi. Please check out the original at https://www.furaffinity.net/view/42028638 . I also wrote a story to go with it:

The Poke-Nursery was buzzing with activity. In the art room, the recent arrivals Monarisu and her transformed counterpart Atoashi were seated down clad in disposable diapers. Monarisu had the letters ABC on the front of her diaper and Atoashi had the numbers 123 on her diaper panel.

Although they were not officially Pokemon, Mewtwo had been manipulating tele-chronomatic powers to retrieve the Time-Space Monsters from all the eras so he could add them to his neverending nursery collection of cute Pokemon or pre-Pokemon in their case.

Originally Monarisu was at Pisa, but was sucked up by Mewtwo's time and space force. At the same time he had drained the squirrel's powers so she could not escape or transform. At first Monarisu's power level of 920 seemed to be all there was, but then the energy tanks which stored the drained power spiked up to 7700.

Mewtwo was surprised at first. The side effect of this draining had caused Monarisu’s super form to separate, making two individuals appear in the nursery. Mewtwo was pleased with this happy accident, since he now had two squirrels to add to the Poke-Nursery. And all that extra power, made for renewable energy that kept the power grid of the Poke-Nursery going at full capacity.

At first the two squirrels were nervous about their surroundings. Already they missed the Renaissance period. They looked around and saw that the room was brightly coloured in a friendly, peaceful kind of way. To their delight, there was an abundance of paper, paint pots, brushes and other art materials.

Monarisu squealed with excitement and Atoashi gasped in wonder. They had no idea why they had been brought here or what was with the odd padding they were wearing, but the art materials provided for them allowed them to do the one thing they enjoyed doing the most; painting.

Monarisu gathered some small pots of poster paint and paper. Atoashi set up an easel with thick sheets of watercolour paper, then got a palette and the essential colours red, yellow, blue, black and white. They momentarily forgot they were captives and began to paint.

The little squirrel Monarisu did finger painting with her front paws. This was odd, because in the Renaissance she used to have the talent to paint photographic portraits. The same applied to Atoashi who was painting an abstract picture instead of the still life she was used to doing.

They didn't know it, but Mewtwo had mentally regressed the two squirrels into toddler-like states and had taken measures to limit their agility and strength so they could not fight their way out of the Poke-Nursery. But their mind was so fixed on their painting, they weren't even thinking about escape.

Suddenly a little girl with scarlet eyes and green hair tied in two ponytails with a pink hair bow and wearing a disposable diaper and short red dress, barged into the room. This was the Time-Space Monsters' archnemesis Petra Fina Dagma, who would stop at nothing to control the cute monsters and change history for her own selfish desires.

It turned out that she had been caught in Mewtwo's time and space force through mid time travel, causing her to physically regress into a toddler while retaining some memories in her fractured mentally regressed mind. She recognised the two squirrels whom she had failed to reclaim in her previous time heist.

Monarisu remembered the lady who had stamped her forehead, twisted her body into something monstrous and fierce and messed up her mind into doing her bidding. This girl certainly did have an uncanny resemblance to the evil Time Pilfer Lady who had terrorised her. Atoashi looked at the girl suspiciously wondering if she was their playmate or a nursery bully.

"Ha! Found you two squiggles!" she babbled. She reached down the side of her diaper and took out her notorious P-shaped stamp with the eye glyph. "You are mine to command!". Monarisu looked timid and chattered her teeth nervously. Atoashi glared at Petra.

The scary toddler stepped forward near Monarisu and thrust her stamp right on the front of her diaper, replacing the letter B on the panel with the letter P with its unblinking eye in the middle. The little squirrel squeaked. Petra quickly toddled towards Atoashi and made the same stamp mark on her diaper.

"Now you're under my control!" Petra declared, holding the stamp triumphantly in the air. Both squirrels felt strange. Their bellies rumbled audibly and they didn't feel so good. The P-mark on their diapers was not affecting their minds, but it was sure doing something to them.

They had little time to wonder what Petra had done, when they found themselves wetting and soiling their diapers. "Ha! Take that you little stinkers!" Petra taunted them "You're helpless. There's no one to save you this time! Oh did I say time?".

"What is going on here?" came a feminine voice. One of the many carers Nurse Awe entered the art room. She was a fair-skinned lady with brown eyes and two zig-zag styled streams on her gunmetal coloured hair. The sight of her was reassuring for the two squirrels.

"What are you doing in the Poke-Nursery?" Nurse Awe asked Petra. "Playing my favourite game, lady" the toddler replied. "You're not supposed to be here without an appointment" the nurse told her "Where are your parents?". "Who cares?" Petra snapped.

"That will not do" Nurse Awe said. She picked up the troublesome toddler, who began kicking and yelling. "Let me go! Put me down! I'm not finished with my minions!". "I'm taking you to a carer" the nurse said "We'll find out where you belong and have you home soon enough. Now stop struggling!".

"No! I'm staying!" Petra cried, throwing a temper tantrum. "And you won't be needing this" Nurse Awe said sternly, taking the stamp from the brat and pocketing it. "Sit tight my little Poke babies" she said to Monarisu and Atoashi "I'll be back once she's out of here".

So Nurse Awe carried Petra out of the art room and straight to the reception where they would contact the welfare authorities to see what was to be done with Petra. It was a relief to the two squirrels that their enemy was off their back, but their used diapers still had her evil mark on them.

Later Nurse Awe returned with two baby bottles of Moomoo Milk and a diaper bag "Come sweeties" she cooed softly "I'll change you and feed you". Soothed by the gentle nurse's voice, the two squirrels trudged towards her and allowed her to lay them on the changing pad which she unrolled.

In a short amount of time, Nurse Awe removed the wet and messy diapers and threw them in the garbage along with the nasty P-marks. "Don't you worry about that troublesome girl" the nurse said as she unfolded new diapers "She will be taken care of. She won't be decorating any more of your diapers or bullying you again".

Comforted, both Monarisu and Atoashi lay back as the nurse fastened the clean diapers on them. Their diapers had the same colourful letter and number prints as the first ones they wore. Nurse Awe cradled both squirrels in her arms, sat on a chair and bottle fed them their Moomoo Milk.

The two squirrels happily suckled the delicious and cool milk. It reversed the effects of the P-mark immediately and filled their bellies nicely. It felt good to be babied and cared for by Nurse Awe, even if they were part of Mewtwo's collection. With the care and attention they were getting, they would never want to leave.