I believe you need either 35 or 45. one of the two.
you need to complete the game. if not, collect 80 shine sprites
you need to have enough shine sprites (or blue coins i don't know) but in super Mario 63 you can only make the rocket nozzle appear by getting the first key
Rocket Nozzle
between 30 or 40
To get the turbo nozzle in you need approximately 25 shine sprites. You will then chase shadow Mario across Delfino Plaza. After you have squirted him with enough water, he will drop the turbo nozzles and leave. To get the rocket nozzle you need approximately 30 shine sprites. Use the same method as before, and you will have all three nozzles at your disposal while in Delfino Plaza. (Note: these instructions only work in Delfino Plaza. There are some worlds you can enter and get these nozzles)
For most episodes, you just have to unlock it in another episode. To unlock it in Delfino Plaza, you must first obtain 30 Shine Sprites, get the Yoshi, (Also obtained by getting 30 Shine Sprites) and the Turbo Nozzle (Also obtained by getting 30 Shine Sprites) from Shadow Mario in Delfino Plaza. Shadow Mario will then carry the rocket nozzle around.
you need to complete the game. if not, collect 80 shine sprites
120
you need to have enough shine sprites (or blue coins i don't know) but in super Mario 63 you can only make the rocket nozzle appear by getting the first key
Rocket Nozzle
89
You Need To Get A Certain Amount Of Shine Sprites. 30-36. once you go back to delfin plaza with that amount. shadow Mario should appear with it. beat him and you get it in delfino plaza.
between 30 or 40
I know that you have to get 50 Shine Sprites to get the zoom nozzle and Yoshi, but I have no clue about the rocket.
noki bay. you need 20 shine sprites to get it.
complete all the levels and find the ??? ones
It depends on how mane shine sprites you collected maybe over 70 shines you will get there