Probably far from exhaustive, that's taken from my notes so if it can help :
Basic :
It's a slow moving multihit projectile. It rocks.
If the leaf gets caught in a slope, it will disappear if the slope is about 20° or higher, but it it's a small slope, it will follow the curve and start going upwards instead.
If the leaf is shot from a slope, il will still be shot horizontally.
The leaf slowly decelerate so if you want to get the most hitstun and damage out of it you want to catch the victim at the end of its trajectory. Shooting it from too close will get you punished.
There can only be one razor leaf on screen at once. The game checks if there is a leaf on frame 1 so you have to wait until the previous leaf is gone to press B.
Because of this, if they break the leaf, feel free to shoot another one sooner.
There is a tilt and a smash version of this move. The Smash version goes a bit further but lasts the same amount of time.
You can fastfall during this move
Advanced :
You can b reverse and wavebounce it for various trajectory tricks
They have about 4 frames to do something between two hits if they shield it, from what I can tell. Not enough to grab or jump, but if they have a very fast usmash or an armored/invincible upB, don't rush in.
Shooting it at about head level should hit whether the opponent stays on the floor or short hops. They can either full hop, or deal with it somehow.
It cancels out with most other projectiles, but has a slower startup and recovery than most. tldr : don't spam it, aim it.
From a tilt razor leaf, you can do a nair, fair or grab. dtilt to tech chase if they CC it. From a smash razor leaf, you can do a rar bair and that's about it.
It's also very great to edgeguard, most people won't do a dair offstage so shoot them underneath them.
It can be used to cover your recovery.
Situationnal :
If the leaf gets caught with a rising platform, it will stop moving horizontally, making for interesting tricks on FoD in example
It the opponent reflects it when it's decelerated, it will not hit you back, it will pretty much stay right in front of where it was reflected
It can't be ledge cancelled, but you can slip from onstage to offstage during the move, kind of like the bowser fortress hog
It stops all momentum so if the leaf goes through the opponent and you dsmash them back into it, they will be stopped by the leaf, no matter how much % they had