Thankfully, we have four independant tricks that let us gain more height than normal (three of which are useful here):
- reverse wall jumping, which allows us to walljump in reverse - instead of the knockback going away from the wall, it goes to the wall instead. Needs to be done from a standstill, not useful here.
- damage canceling; we can cancel out of Goku's taking damage state if we do any action during the first few frames.
- walljumping → LR rush. Walljumping pushes us away from the wall. However, in the first frame that we exit the walljumping state, LR rush and we're back on it, allowing infinite scaling assuming a perpendicular flat surface.
- walljumping knockback cancel. Holding the direction going to the wall after jumping away from it "cancels" most of our knockback by putting Goku to a much lower speed.
Combining this, we can scale the pit in its entirety. The first wall is flat and high enough to reach with a jump, so we scale it with walljumping → LR rush.
The second wall is much trickier: it's out of our reach by a normal jump. Thankfully, since we're in the pit that drops boulders, we can take damage off those. By jumping, divekicking "in reverse" at peak height to use the initial divekick phase (gaining us a further vertical advantage and pushing Goku to the left as well) then taking damage at the peak of our height, we get a bunch of height in the middle of the pit, enough to reach the wall. The only thing left to do is reach the wall with an LR rush and walljump → LR rush again.
The third wall is easier. The only tricky part is the reversed triangle celling at the start, which we can clear with normal walljumps with largely gimped knockback, using the knockback "cancel" trick. Then clear the rest with walljumping → LR rush.
Saves around ~500 frames over the normal route approx.