Here's a mini compilation of info I gathered one day.
SYYG Theorys
Charging the yo-yo off of the edge
WD at the edge then yo-yoing
JCing the yo-yo
Effects
Instant death throws with teleportation
Infinite trapboxes
Infinite jackets
Going through the stage with PKT2
People Who Have Done It
Damian (The guy who discovered it duh)
Flamestar666
Simna
Stages of success
FD
FoD?
What Doesn't Work, but can get a yo-yo off of the edge
UFO WD
Whispy Winds tree
Pushing Ness as he charges the yo-yo
Other useful information
After a WD, Ness can take action on frame 11
The yo-yo usmash hitbox comes out on frame 12
The charge occurrs on frame 13
The yo-yo reaches its maximum length at frame 18
When you teeter off of the edge, Ness spends 13 frames doing an "otto"
After the otto, he goes into "ottowait"
And here's an interesting conversation between Flamestar and Simna who possibly did the glitch.
some more SYYG info guys....make of it what u can:
flamestarr666: ok something odd happened
Simna ibn Sind: yeah?
Simna ibn Sind: u did SYYG?
flamestarr666: i dunno
flamestarr666: i yoyo'ed off the edge
flamestarr666: and i was messing around
flamestarr666: then i pkt's back onto the edge becaise i jumped off
flamestarr666: and ganon was near the edge
flamestarr666: and i hit him like 4 times
flamestarr666: 0-like... 78
Simna ibn Sind: !!! did u record it?
flamestarr666: no
flamestarr666: i have no recording device
flamestarr666: T______________T
Simna ibn Sind: everlasting jacket....that's syyg
flamestarr666: no way!
flamestarr666: omg
flamestarr666: let me try ro recreate it
Simna ibn Sind: what happened after?
Simna ibn Sind: is the match still open?
flamestarr666: it's in training
Simna ibn Sind: have u reset or anything?
flamestarr666: no
flamestarr666: i paused
flamestarr666: that's it
Simna ibn Sind: sweetspot the edge with pk thunder
flamestarr666: nothing
flamestarr666: i died before though
Simna ibn Sind: o
flamestarr666: i diddn't make it back on
Simna ibn Sind: wait try throwing dorf
flamestarr666: normal
Simna ibn Sind: hmmm.
Simna ibn Sind: i guess it disarms when u die
flamestarr666: all you heard was zapzapzapzap
Simna ibn Sind: good progress tho
flamestarr666: then he went flying
flamestarr666: wanna know something weird
Simna ibn Sind: yeah
Simna ibn Sind: i wanna know weverything
Simna ibn Sind: everything*
flamestarr666: ok this is what i did
flamestarr666: i was wd to the edge, faling pff
flamestarr666: i did it 4 times about
flamestarr666: i pk'ed back on
Simna ibn Sind: faling pff?
flamestarr666: falling off*
Simna ibn Sind: of
flamestarr666: wding off the edge
Simna ibn Sind: oh*
flamestarr666: so i pk'ed back on the legde
flamestarr666: i'm on FD
flamestarr666: about a roll distance away
flamestarr666: i grabed ganon and tossed him to the edge
flamestarr666: i paused, because iu had a phone call
flamestarr666: i did a normal yyg
flamestarr666: then i attached it to myself
flamestarr666: spiked him up
flamestarr666: then i threw him to the middle of the stage
flamestarr666: i nailed myself with the pk thunder straight down
flamestarr666: you know to tget that static affect
Simna ibn Sind: yeah
flamestarr666: i throw him again
flamestarr666: no
flamestarr666: i yoyo's off the edge like 5 times
flamestarr666: then i threw him
Simna ibn Sind: were u able to charge it?
flamestarr666: yeah
flamestarr666: 2nd one i missed i think
flamestarr666: might of been the 3rd
Simna ibn Sind: how much did u charge them?
flamestarr666: all the way
Simna ibn Sind: ok
flamestarr666: so then, i jumped off, i was like w/e, right
flamestarr666: i pked the edge back near the bottom stright up
flamestarr666: i well
flamestarr666: kinda left
flamestarr666: mostly up
flamestarr666: and i hit ganon's barely
flamestarr666: and i o heard was zapzapzapzap
flamestarr666: then i died
flamestarr666: i thought i sweetspoted it, i guess i didn't and i missed
Simna ibn Sind: did u bounce off the wall or what?
flamestarr666: no
flamestarr666: i fell
Simna ibn Sind: were u too far or did u just kinda fall?
Simna ibn Sind: did u reach the edge at all?
flamestarr666: i wasn't paying attention
flamestarr666: i think i did
Simna ibn Sind: because that's another syyg effect
Simna ibn Sind: PK Thundering thru solid objects...u may very well have gotten to the edge but gone thru it then fall down out the bottom
flamestarr666: i thought i saw some grafical glitches on ness
flamestarr666: maybe it was the multiple impact
Simna ibn Sind: yeah i believe those happen too
Simna ibn Sind: now that we have more proof that this does in fact exist...we must figure out the exacts behind it^_^
flamestarr666: it's insane
flamestarr666: if we can figure this out
flamestarr666: ness will broken
flamestarr666: lol
flamestarr666: you better take me with you
flamestarr666: if you go to a tournament
Simna ibn Sind: lol
Simna ibn Sind: as soon as i can do the SYYG whenever i want
Simna ibn Sind: first thing im gonna do is
Simna ibn Sind: im gonna go to socal
Simna ibn Sind: and im gonna have a bowser challenge
flamestarr666: LOL
Simna ibn Sind: im gonna thunder jacket and spam pk fire
Simna ibn Sind: that will end the match
flamestarr666: totoally
flamestarr666: i can't yyg
flamestarr666: it won't let me
flamestarr666: dude i can't
Simna ibn Sind: try again
flamestarr666: i did
flamestarr666: like 20 times
Simna ibn Sind: use fair, then try again
flamestarr666: i fif
flamestarr666: didi*
flamestarr666: this is pissing me off
Simna ibn Sind: u broke the game
flamestarr666: lol
Simna ibn Sind: u r banned from tournament
flamestarr666: i just did it
flamestarr666: i reset
flamestarr666: on training
flamestarr666: i dunno if it was just me
flamestarr666: but i swore i felt a rumble when i was midair
flamestarr666: i dunno
Simna ibn Sind: rumble?
flamestarr666: my controller
Simna ibn Sind: when in midair?
flamestarr666: yes
flamestarr666: i jumped off
flamestarr666: and i felt a slight shake
flamestarr666: i dunno if it was just me
flamestarr666: or something
Simna ibn Sind: its the gods
flamestarr666: lol
Simna ibn Sind: warning u not to proceed
Simna ibn Sind: u are walking into broken territory
flamestarr666: can you ttg with the d smash?
Simna ibn Sind: u can yyg dsmash but we looked into that and found it mostly useless
flamestarr666: how so?
Simna ibn Sind: ya know how with upsmash u have to hit the opponent for it to work?
flamestarr666: yeah?
Simna ibn Sind: with dsmash yyg u have to hit the opponent AND get hit yourself
flamestarr666: o.0
flamestarr666: how do you do that?
Simna ibn Sind: i did it as an edgeguard vs. marth
flamestarr666: oh
Simna ibn Sind: dsmash as he is coming up, then it makes him drop a bit, then release, then he upBs and hits u
flamestarr666: oh ok
Simna ibn Sind: hey
flamestarr666: hmm?
Simna ibn Sind: when u yoyo'd over the edge
Simna ibn Sind: how far over the edge was the yoyo?
flamestarr666: i'm not sure
flamestarr666: like...
Simna ibn Sind: was it like hanging straight down string and all?
flamestarr666: i think i tipped the edge
flamestarr666: like, at a 45 degree angel
flamestarr666: angle*
Simna ibn Sind: was the string over or just the head?
flamestarr666: string was about 40% off the egde
flamestarr666: edge*
Simna ibn Sind: cool
Simna ibn Sind: good info
flamestarr666: the string seemed to bend
flamestarr666: almost wanting to go straight down
Simna ibn Sind: but not quite?
flamestarr666: almost like a sharp angle
flamestarr666: you knw normally it's like curves
flamestarr666: it wad kinda just staight
flamestarr666: then down
Simna ibn Sind: like a straight diagonal line away from ness?
flamestarr666: kinda
flamestarr666: like 50 stright
flamestarr666: slight curve
flamestarr666: then 45 degrees
And the sequel!!!
[11:08PM] SimnaibnSind: i did have slight graphicalhickups
[11:09PM] SimnaibnSind: nothing big tho
[11:09PM] flamestarr666: LOL you posted my message?
[11:09PM] SimnaibnSind: yeah
[11:09PM] SimnaibnSind: ^_^
thanks for the heads up
my theory soming up
[11:20PM] flamestarr666: idon't think it has to do wuth the edge
[11:20PM] flamestarr666: i think it had to so with jump canceling the smash
[11:20PM] SimnaibnSind: really?
[11:20PM] flamestarr666: while you're moving
[11:20PM] flamestarr666: i think so
[11:20PM] SimnaibnSind: maybe a combination of both?
[11:20PM] flamestarr666: probab;y
[11:20PM] flamestarr666: because check this out
[11:21PM] flamestarr666: the last time, i missed my smash
[11:21PM] flamestarr666: and jumpped
[11:21PM] flamestarr666: like a n0b
[11:21PM] flamestarr666: n00b*
[11:21PM] flamestarr666: that's when i started ****ing around
[11:22PM] flamestarr666: i'm thinking this...
[11:22PM] flamestarr666: i think it has to do witht he yoyo getting dragged off the edge
[11:23PM] flamestarr666: and the hitbox temp staying on the egde while it sharges
[11:23PM] flamestarr666: charges*
[11:24PM] flamestarr666: which would explain the jump cancel, because caneling the crouch animation would make then yoyo probab;y come out closer
[11:24PM] flamestarr666: and the hitbox would stay on the egde
[11:24PM] SimnaibnSind: hey
[11:24PM] flamestarr666: and snap onto the place where it was suppose to be