STAR PLATINUM.... REQUIEM!
First, ability.
Star platinum requiem has the ability to stop time on anything and anyone. No matter how far away or what their ability is, star platinum requiem can stop time on them. The time stop is infinite for however long the user wants it. Maybe you just want to trap someone forever in time stop? You can do that!
EXAMPLES (if you don't really understand):
Stopping time on a couple of blood cells for someone, making a blood clot. Stopping time on everything except the heads of your enemies and making them watch as you make them donuts but they don't die because everything is paused. Pausing the electricity in someone's brain so they can't think. Aging? Paused. Anything that can be paused can be paused.
Description of looks:
It's star platinum, but near it's heart on it's chest the arrow is placed, showing the requiem is made to protect the people he holds dear. Star platinum's eyes glow a heavenly white. Floating behind it, a large gold stopwatch. When star platinum requiem uses it's ability on anything the stopwatch stops, but if it's not a full time stop (such as pausing someone's legs) another hand on the watch appears and starts turning while the first hand stays still.
Stand stats time!
Speed: Stops time for as long as he wants, doesn't need speed
Precision: Stops time for as long as he wants, doesn't need precision (But requiem improves abilities and y'know, it's star platinum.)
Durability: Stops time on the thing that is gonna damage it, doesn't take damage. (But it's star platinum and you know how it be.)
Range: Infinite for where the user can time stop, stand effective range is 20 meters
Potential: E (requiem is the peak of a stand)
Power: A+
BACKSTORY
Requiem stands gain their ability because of the requiem arrow of course, but their ability is given from what they need in the situation. Chariot requiem? That came about because Polnarref wanted to protect the arrow. Bites the dust? (I know its controversial) It came from Kira wanting to not be found out for his crimes.
Here's how star platinum requiem would get it's ability:
Pucci is accelerating time fast. Giorno is there in this alternate universe, and Giorno isn't bonded to the arrow forever. In an act of desperation to save everyone, Jotaro stabs himself with the requiem arrow knowing if he wasn't worthy he would die. His only goal in the moment is to protect everyone and stop Pucci from accelerating time further. The requiem arrow goes into star platinum, and fuses. Jotaro pauses the universe speeding up (Like Pucci speeding the universe up, nobody is effected.) and also pauses Pucci. (insert Jotaro killing Pucci and part ends)
Sorry if this was long, once I get on a creative roll I just don't stop, and also if there some elements that seem way too OP for even a requiem stand, let me know. It's my second time thinking of a stand and my first one was way different.