PIT control

When the adults and babies are separated, you can only have control of one of the pairs at a time. You can tell which pair you have control of by looking at the action command icons: if A and B are brighter, you have control of the adults, and if X and Y are brighter, you have control of the babies. If there are no action command icons, you don't have control of anyone - I will refer to this situation as a cutscene.

If you press a direction on the d-pad, the characters that you have control of are the ones that will move. In other words, characters can walk only if you have control of them. Here are other actions characters can do only if you have control of them: change action commands, talk to NPCs, read signs, hammer, baby drill, spin jump, and bros. ball.

If you have control of the adults and want to gain control of the babies, you must press X or Y while both adults are on the ground. If at least one of the adults is off the ground and you press X, Baby Mario will jump but you will NOT gain control of the babies. In this way it is possible for characters to jump even if you don't have control of them. If Baby Mario has water in him and you have control of the adults but at least one of the adults is off the ground, pressing Y will make Baby Luigi hammer Baby Mario, but you will not gain control of the babies. So, like jumping, it is also possible to do this action even if don't have control of the babies. This is actually used in the TAS: https://youtu.be/9tttgnGVEL8?t=3754