Ike grab glitch
How to perform
Two players are required for this glitch, however only one needs to do anything. The first player must select Ike. The other player must be King Dedede. King Dedede does not have to be controlled by a human player. King Dedede's feet must be touching the bottom edge of the fin that is in the middle on Corneria when Ike grabs him for this to work. The position can be easily viewed by going to training as Ike against King Dedede and using Ike's Bair on Dedede towards the fin once without moving him. If Ike grabs him there without moving Dedede, it will work. Doing this glitch correctly will result in King Dedede being stuck in a strange animation. The game will emit a buzzing noise. If done in training, the player can slow down the speed to see that King Dedede is actually bumping between the fin and Ike. This reveals that the buzzing noise is actually the sound of said bumping being played in extremely rapid succession. Also, in this state, the throw never ends unless Ike pummels him or presses a directional button. It doesn't do any damage, however.
This glitch may also be performed at the head of the ship. King Dedede must have his right foot almost touch the tip of the curve on the head.
It is possible that this glitch is caused by King Dedede rapidly alternating between his "grabbed high" and "grabbed low" animations. This alternation is usually triggered only once based on whether the grabbed character's feet are on the ground during the grab, but it is possible that the exact placement of the glitch combined with Corneria's constant movement results in a rapid alternation between "on ground" and "off ground". However, this does not explain why Dedede does not naturally escape the grab.