In terms of movement and air speed, Cloud especially when he fully charges limit has better mobility, and overall has better movement and air speed when compared to Link, but in this case we are talking about fast as in their ability to effectively put out active hitboxes to keep opponents at bay, and the ability to pressure an opponent when shielding.
Even though some moves of Cloud's have a faster start up, Young Link does better in terms of shield pressure, and can initiate more moves due to many of his attacks being safe on shield. Young Link's bombs can be utilized with z drops to put out more hitboxes to rack up percentage faster. One unique thing with bombs is that you can juggle bombs by z-dropping and immediately following up with an aerial attack to recatch the bomb, essentially allowing you to pressure while still holding the bombs with aerials, and dropping bombs does not explode them unless you hard toss them which is useful for edge guarding and covering areas like platforms. Bombs can also be used out of shield by buffering jump then immediately Z dropping which comes out around frame 4-5, faster than nair out of shield. Bombs offer unique mixups that further helps Young Link to pressure opponents especially on shield. Not to forget that utilizing his kit effectively further pressures by putting out projectile hitboxes and allows you to influence your opponents maneuvering, creating openings for yourself.
Essentially Young Link has very good options that helps him excel at close ranges and at a distance because of his projectiles, and many of his moves being safe on shield. If you check ultimateframedata, you can see that various moves of Young Link have low negative numbers regarding "On Shield". Cloud has more moves that come out faster, but has less reliable moves to pressure shield, but better range and overall kill power.