Super Mario Bros./Minus World Ending Strategy

See i_o_l's WR video for the general strategy. This only goes into detail on the non-obvious things going on. Make sure you actually play the Famicom Disk System version.

Level by level explanations

World 1-1

When you go into the underground section, start holding "right" when Mario has fallen about half the way down and jump as soon as you're able, trying to land on the very edge of the bricks in the middle. The farther to the left you land, the sooner you start accelerating to full speed. When the pipe transition happens, you should have 380 on the timer.

Later just hit the flagpole at the very top. If you have 370 remaining on the timer, the level is flawless. If you have 369 remaining on the timer, it can also be flawless, but it's very likely you missed the framerule.

World 1-2 (Warp to -1)

The first difficult part here is jumping over the Koopa with the Goomba directly behind it. The best way to do it is to run at full speed and do a jump where you hold A for 1 to 3 frames and then immediately jump again.

There are two different methods to glitch through the wall at the end of the level and reach the Minus World. One is to become big Mario and glitch through the wall as in the WR video. Getting the perfect framerule is extremely precise.
The other is to go through the pipe as small Mario. This trick is explained in detail on the main page and is very difficult, but would allow for a World Record while doing the Minus Worlds completely safely.

World -1

A very easy level except for the flagpole glitch at the end. If you don't do it, hit the flagpole in the middle, so that you go into the castle without touching the ground.
If you want to do it, let go off right, drop down landing just in front of the block below the flagpole and immediately swim. If you spend more than a few frames on the ground, you will trigger the fireworks (which is still faster than not doing the flagpole). To make sure that you don't get the fireworks, land well before the flagpole on the ground and walk the rest of the way.

World -2

A very simple level and one of the few levels, where it doesn't matter, how high you hit the flagpole.
There are some very tricky framerules, so check the patterns of the Cheep Cheeps with the strategies you use before doing attempts.

World -3

There are 2 turnarounds in this level. As big Mario it is faster to break through the ceiling instead. It is faster still to glitch through the ceiling with a duck-jump into a corner, but also more difficult.
As small Mario you could theoretically glitch through the wall and skip the turnarounds too, but it is too difficult. When doing the turnarounds start holding left and bump into the opposing walls. A single frame can be saved by stomping the Blooper before the first turnaround.

RTA WR and TAS comparison

TODO