There's a "Known Issues" section in the OP, but there are literally zero known issues listed.

Should be put in known issues...

I had entered a multiplayer match and waited a bit for the host to start his "1v1 match", The minute it started i noticed my character was in a sudden death fighting a sandbag... It was really confusing because i wasn't even controlling my character, Black Mage. After the fight finished (it only had one life in the match) it brought me to the main menu screen, I tried to join multiplayer again but it brought me to this screen (http://imgur.com/YWTdX7O), and now i can't go anywhere else or choose a character. I don't know what to do with it.

Samus's up throw doesn't work on Megaman...mostly.

Sorry. I have looked through and this is true. I thought it was the suggestion box, not the forums

Link picked up an E-Tank and started spazzing like this.

update: it also doesn't work on Ness.

full detail: When Samus's up throws MM or Ness, most of the time they won't receive the final zap and will briefly stunned in midair before falling down like nothing happened.

Black Mage's Warp (Up Special) ring can get stuck under the 'lip' of Final Destination, however if you release the 'B' button, you will teleport above the stage and land on it instead, or instantly grab the ledge, even though the ring was under the ledge when it was activated.

Also, as Sheik, if you fire a needle right before you land, you will land with no ending lag, instead standing (and sliding if you have enough vertical momentum). If timed correctly, the needle will actually be fired (hitting someone if they were right in front of Sheik), and Sheik will land with no lag.

When me and my friend were playing Final Destination with Smash Balls on, one Smash Ball appeared in the ground and wouldn't move. Later, I was playing by myself on Temple and a Smash Ball appeared in the ground, not being able to move. I don't know if this was already reported or not, but I am reporting this now.

Certain characters cant reach Smash Balls under some cicumstances. For example, Black Mage cant reach it at all on Chaos Shrine in most cases.

In replays the assist trophies never come out in the right order. It's like it saves the buton inputs but not the trophies. I had a great online mode replay, but when I watch it, Krillin ALWAYS comes out instead of Starfy.

There are victory themes that do not fade at the right time.

Take a listen to Lloyd's theme in the game and the one at the DOJO!!.

Then you'll see the difference.

The character's voices can still be heard during taunts, even if Voice is turned to 0 in Settings.

I am pretty sure this is something new. I found a 's glitch. When I was about to take his second stock (CPU) he used U-Special and the spring acted normal but went down...
Here's the replay file, happened when he had two stocks: