Recently there has been much discussion on whether there should be a rule added to prevent the abuse of pausing to prevent the use of input buffering and to react to situations that would normally not be possible to react to.
Personally I am leaning towards adding such a rule to not use pausing for such matters. But pausing shouldn't be outright restricted or limited as things simply come up or we have to sneeze or itch.
If there is suspicion of pause abuse, we would simply request for the replay file so we can look into the inputs via Cheat Engine.
I think the most advantagous way of abusing input buffering is for MTS chaining. While performing a MTS, pause at the moment you want to repress A. Buffer the direction you need to turn towards and hold both shoulder buttons. Then hold A and repeatedly press on the side attack button. The main advantage of this is to instantly turn in the opposite direction at full turning strength in a frame. There is a strong indication that this leads to faster speeds when MTS chaining. It's probably not that much of an advantage time-wise but it's just not the kind of experience we want to promote.
You can pause in anticipation of getting a rare double shift boost to make the proper adjustments depending on whehter or not you get the double/triple shift boost or not. That takes away from the player skill involved.
However with speedruns, I think it's fine to allow pause abuse due to RTA timing as opposed to in-game timing.
Feel free to add onto the discussion and propose how the rule should be written out, which I will do so in the near future myself.