That's right, up angled fsmash kills better. I don't know why. It does.
Down angled fsmash kills worse.
One problem of doing up angled is that you might jump or something, and it's against most players' habit (lots of people hold down a lot for crouch canceling which isn't actually in brawl lol)
So, if you're keeping tap jump on, up angling fsmash can be somewhat awkward.
However. The best players always have habits of doing the most efficient thing they need to do in their situation. Being able to angle the fsmash correctly for certain situations will definitely help Samus players find kills easier.
tl;dr
Press cstick to fsmash and immediately press up on control stick (*afterwards*)
Timing is easy, but the up on the control stick must be during the windup for the punch.
note that sometimes you will miss if they are under your arm lolol
note also bombs set up fsmash pretty cool.
Down angled fsmash kills worse.
One problem of doing up angled is that you might jump or something, and it's against most players' habit (lots of people hold down a lot for crouch canceling which isn't actually in brawl lol)
So, if you're keeping tap jump on, up angling fsmash can be somewhat awkward.
However. The best players always have habits of doing the most efficient thing they need to do in their situation. Being able to angle the fsmash correctly for certain situations will definitely help Samus players find kills easier.
tl;dr
Press cstick to fsmash and immediately press up on control stick (*afterwards*)
Timing is easy, but the up on the control stick must be during the windup for the punch.
note that sometimes you will miss if they are under your arm lolol
note also bombs set up fsmash pretty cool.