Weirdshot (Sometimes known as A-slide clipping) is a trick which causes the hookshot or bow's camera to temporarily detach from Link's position, allowing the player to reach normally unreachable switches or hookshottable objects.
With different timings, a Weirdshot can shift link's camera to different positions. In the Japanese version of the game, there is even a frame which allows Link's camera to shift into the air above him (Though this frame crashes on the English versions)
When Link gains a large enough backwards velocity, his model can begin to break up and distort when the analogue stick is held in any position for a specific amount of time. During this distortion, the different parts of Link's model will offset in such a way that it can cause Link's head position to be under the ground or in the air. Since going into first person view with the hookshot or the bow locks the camera at the position of Link's head, doing so in the middle of the distortion described will allow Link to shoot the bow or hookshot from this offset position.
It's worth noting that although the parts of Link's model distort and become offset, his 'real position' will always be in its regular place. This means that any cancellation of the Weirdshot will take Link back to the position where the Weirdshot was performed, since this is his real position.
† The second frame of the 7th black flash or the first frame of the 7th red flash (Same as HESS and Megaflip).
†† If your roll was the first frame possible, you have all 3 frames between the beginning of the bomb explosion and the red effect (damage frame) to input hookshot/bow. If you get a second frame roll, then you cannot input hookshot/bow on the first explosion frame and thus only have 2 frames for the input.
††† The number of frames between hookshot/bow input and releasing Z is what changes the variation of Weirdshot. The effects on the Japanese and English versions of the game are different from one another and are listed below:
It is common to use pause-buffering with this trick as there are many inputs that need to be a certain timing for a Weirdshot to work, especially on English where advancing too many frames after the hookshot/bow input without releasing Z will crash the game. Being short on bombs is another good reason to pause-buffer this trick.
This video shows both the buffered and the unbuffered method of doing the Weirdshot, and the 2 different outcomes of the trick.
Pressing A, B, Z, R or using any C-button except the button for hookshot/bow that you used to Weirdshot will immediately cancel the Weirdshot. Taking any damage whilst in a Weirdshot state will also cancel it.
Each Weirdshot can be used multiple times. You can hookshot/bow multiple targets with a single Weirdshot. This is useful in Oceanside Spiderhouse where 3 Skulltulas can be hit from out of bounds with a Weirdshot.
Out of the 5 items that you can equip to Weirdshot (Hookshot, Bow, Fire Arrows, Ice Arrows and Light Arrows), after the Weirdshot has been performed, you may not change between them. eg. you can only fire one type of arrow per Weirdshot.
A Weirdshot can be used in the Gyorg fight in order to skip the introduction cutscene by damaging him before hitting the trigger to activate the cutscene. This causes the fight to start without the regular boss music.