Pinning is affected by many factors. The pinned player's health, and muscle power. As well as the pinner's Knockout Meter.

Each player has 2400 health, and muscle power that starts at 0 and goes to 2400. The way muscle power is gained varies from character to character; some characters get muscle power from half the damage they take, and some gain muscle power from 100% of the damage they deal. Most characters are the latter.

The knockout meter starts at 0, and stops at 240. This meter then resets after the knocked out player gets up. Each attack has a set addition to this meter, some give a lot, some dont give so much. The players knockout meter resets if they deal damage to another player.

When a player is getting pinned, a value is calculated with the pinned players knockout meter, muscle power, and health. This value is then reduced by 1, every single time you press any of the 4 main buttons (x, circle, triangle, square). You're limited to 1 input per frame. If you dont reduce the value to 0 before 3s are over, you are pinned.

I figured out a formula with a very very small margin of error: MAX(MIN(CEILING(CEILING(70-(Health/24)-(Muscle/48))+(Knockout/20)),70),0)

I know it looks weird, I'm pretty sure they have some weird Ceiling & flooring action going on. Cant seem to figure out the exact combination, they probably add a small decimal too. With enough time i can figure out the exact exact formula, but this is accurate enough imo.

Bots tend to do 12 inputs a second, when in pins (1 input per 5 frames). So, this means we can have a value of 36 and pin the bot. With a 240 knockout meter, you can theoretically pin a bot at 1127 health (47%).