Go into training mode and count how many seconds it takes for the bomb to come out and for the boomerang to go away.
And then practice counting in your head, "1 mississippi, 2 mississippi..."
The animation for about-to-throw-the-boomerang is very obvious and long,
and (Adult) Link makes a very obvious sound at the beginning of throwing animation.
If YL does this too then kindly turn up the volume a bit and listen for that.
If YL catches the boomerang while doing nothing (i.e. not doing an aerial), then he'll freeze for a 19-frame catching animation!
So that's either an opportunity to punish,
Or YL being forced to do an aerial.
Maybe you can fair or bair the boomerangs away.
There's probably "safe zones" from projectiles since Links can't throw projectiles in any direction.
Boomerang can only be thrown so diagonal.
Bomb's can only go forward, arc, down, z-drop, up, back.
(z-drop is quick. One more reason not to be below a Link).
Note: the rest of the stuff is based off of Adult Link. I assume this also applies to Young Link / YL:
Link's hookshot can't grab airborne people at long range (but it still can close to Link's body).
If you don't hear the boomerang whooshing through the air, then that means it's gone.
Close-up boomerangs hurt and start combos well, but they're also unsafe for Link.
YL takes just as long to throw it (but YL's boomerang lasts 10 frames longer).
(Adult) Link's boomerang vanishes if:
- it hits the stage's blast zones
- was out for too long (but how long???)
- you hit Link after the boomerang comes out but before Link finishes his throwing animation (i.e. before Link can start doing something else again). Weird. It's an 18 frame window (for YL too).
Oh, and (Adult) Link's dair has a high hitbox near the hilt that can still KO. So if you think you got KO'd by YL's head, that's probably why.
Bombs fly through the air slowly, too, (at least Adult bombs lol) so practice catching them if you can.
buffer-tech Link's downthrow.
Link's side-throws are lousy at low %.
YL probably has to jump to combo out of down and up throw vs floaties. Dunno if that helps.
Oh, but if YL's upthrow is anything like Adult Link's at high %, then it might KO Jigglypuff.