The Floating Link Glitch puts one, some or all Links on a different layer, depending on how the glitch is executed. This leads to some interesting effects that will be listed below.
Primarily, there exist two forms of FLG: The first one that was discovered, usually just called "Floating Link Glitch", and "Formation Floating Link Glitch".
The following describes the "normal" FLG:
By undergoing some form of knock-back while one or more of the Links hold an item above their head (e.g. a bush, pot, rock, etc.) and then using the X button to select that Link while he is still in the air, you can then walk around in the air as long as you're still carrying the item. The downside is, however, that the majority of the time you are still affected by features on the ground, such as hitboxes or objects, water, and chasms.
One way in which you can undergo knock-back is by getting hit by a bomb's explosion. While one of the Links (not the one getting directly hit by the explosion) is holding an object above his head, get knock-back damage off of the bomb. While the object-holding Link is in the air, select him with X.
Pick up an object with one of the non-green Links and use X to select Green. Charge at a wall with the Pegasus boots, and while charging press L to summon the other Links. Once you've hit the wall and bounced back, use X to select the Link that is holding the object.
Perhaps the easiest method by which to do this glitch is with the Roc's Feather.
Pick up an object with one of the non-green Links, and then use the roc's feather to jump. Once the desired Link is in the air, use X to switch to him.
Note: Anything that can cause damage knockback will be able to cause this glitch (similar to how the bomb works). So the Firerod can be used for this glitch as well.
When experiencing recoil while doing a Jump Slash, FLG is active as long as you keep moving.
This is a very weak form of FLG due to the minor height difference.
In contrast to FLG, there also exists a form of FLG that affects more than one, or all Links and lets you walk around in formation while FLG is active. The differences seem negligible, except that you can still fight with a sword while using Formation FLG.
Using this method, you simply need at least Green to carry an item and then, just as soon as you start a jump slash with any other Link, reunite with any C-Formation. Any Link that does not carry an item can use his sword like always. This can be used to fight difficult enemies, but is not really utilized in the current run since there exist faster strategies. Dropping the item(s) will nullify the effect of FLG immediately.
Again, you want at least Green to carry an item and then switch to a Link without an item. Simply jump with said Link and hold the C-Stick in the desired direction. As you hit the ground again, the Links will reunite, with Formation FLG active.