You should put this in the bug report thread. This thread you just posted in isn't for reporting bugs and glitches.

Characters used: Kirby (me) vs Chibi-robo
Stage: Final Destination
Hazards/items: off
multiple matches: nope

Characters used: Kirby (me) vs Isaac
Stage: Yoshi Story
Multiple matches: no
Items/hazards: off

Characters used: Sora (Me) Bandana Dee (Didn't check name)
Stage: Skull Fortress
Items and Hazards: Both on
Matches: Single
Notable: It wasn't a serious match. I SD'd a couple of times.

Final Destination
Bowser vs Falco
Competitive

***** 1.0.2 has fixes for a lot of the desync bugs we found ******

2 new ones


Both held on Battlefield 3 stocks no time limit

1: Mario vs Ichi
2: Mario vs BDee

Not solid on this, but both seemed to desync on first hit, both were fresh lobbies

2 of them:

Characters used: Mario (Me), Kirby (haaii), Sonic (Forgot) ZSS (Didn't notice).
Stage used: Devil's Machine.
Items: On.
Hazards: If Giygas talking counts, On.
Matches: Single.

Characters used: Luffy (Me), Link (cryW0lf).
Stage used: Final Destination
Items: On.
Matches: Single.

Characters used: Goku (Me) Issac (Forgot)
Stage: Chaos Shrine
Items and Hazards: pokeballs, metal box & Assist trophy only
Matches: Single
Notable: We desync because many pokeballs and AT were summoned(I think)

Characters used: Bowser (Me) VS Mario (?)
Stage: Pokemon Coliseum
Items and Hazards: None
Matches: Single
Notable: The Mario began to roam around like crazy in the opposite direction of me and was trying to attack like I was on the other side. We froze when he actually landed a hit on me.

Characters: Link (Me), Bandanna Dee (Opponent 1), Pit (Opponent 2)
Stage: Final Destination
Items: On
Matches: Single

Characters: Megaman (Me), Jigglypuff (Opponent)
Stage: Waiting Room
Items: Off
Matches: Single
Note: Desynced right at the KO blast effect just as I took out her first stock

Me Marth, them Bandana Dee
Mirror Chamber
I think this was the third game I played in the same room, all with different players.
No items, no hazards.
The game desynced right before the last KO. It was Bandana Dee dying from a star KO, and the star never appeared.

Characters used: Samus (Me), Meta Knight (Opponent).
Stage used: Hidden Leaf Village
Hazards?: Off?
Items: On.
Matches: Single.
Notes: The match was extremely laggy and it desynced right when the game ended.

EDIT: Another one:
Characters used: Pit (Me), Sora (Opponent).
Stage used: Yoshi's Island
Hazards: Off.
Items: On.
Matches: Single.
Notes: This match was also laggy but not as much as the other one.

EDIT: Another one:
Characters used: Pac-Man (Me), Samus (Opponent).
Stage used: [b]Crateria
Hazards: Off
Items: On
Matches: Single

What characters were used: Me: Zelda vs. a Link
What stage was used: Rainbow Route
If you played multiple matches in one lobby or if someone quit your lobby and someone else joined or anything weird like that: Nope. First match of online after firing up the game.
If items were on or hazards were on: None
Anything else notable you think we should know: Say "3," freeze-frames for 7-8 seconds, then continues into the game with a pretty smooth connection. A minute of play later, just hard freeze-frame; 15 seconds of pause later, the room ends itself.

Characters: Kirby (Me) vs Link
Stage: Battlefield
Multiple matches?: no
Hazards/items: off