About two thirds of the way through 2-2, you'll encounter a part in which there's a pipeman that blocks your progress. There are three things you can do in this situation:

1. Wait for the pipeman to go down so you don't get hit. This takes about 3-5 seconds (ish) and I'd highly recommend avoiding this method.

2. Slowly line up so you're stood on the first few pixels of the pipe where you don't take any damage, and jump over the pipeman. This takes a bit to get the line up, however is still faster than option 1. However, there is a third option, also known as "Fast 2-2" or "2-2 Jump" which is easily the fastest option, despite being very difficult.

3. Jump over the pipeman entirely without slowing down. This can be accomplished in two ways. Firstly, you can jump just as you hit the patch of dirt I've circled in red on this screenshot - https://ibb.co/k01ChKv - and then as soon as you land behind the goomba, jump again. This works around 60% of the time for me, and is a pretty precise lineup that is similar to the 1-2 jump in execution.

Alternatively, you can try what I find to be the easier method, lining up a super jump. To do this, run right up to the goomba at full speed, and just as you are about to hit him, press A and then Y (this version of the trick is gamepad only) in quick succession. If done properly, you'll hear the jump sound effect play twice rapidly, and you'll gain enough height to make it over the pipeman and the gap behind him. However, the timing on this trick is very strict, and requires you to press Y a bit after you press A, not at the same time, so it may be better going for the first version of the jump if you can't hit it consistently.