An edge attack (ガケのぼり攻撃 or 崖登り攻撃, Cliff climbing attack) is an attack performed by pressing the attack button while hanging on an edge. This allows the character to get up onto the stage while performing an attack.
In the first three games, once a character has received 100% of damage, they begin to perform a different edge attack than normal. The attacks are usually slower, but do more damage to opponents, although the increase is usually only 3-5%. For example, Yoshi's edge attack involves a quick 6% tail whip, while when at high damage, it becomes a slow 12% headbutt. However, in Smash 4, this effect is removed and the edge attack is the same regardless of damage percent for all characters.
Edge attacks are generally avoided in competitive play due to their slow speed and limited usefulness. Players will often use other techniques or attacks to return to the stage instead. However, players will often mix in edge attacks to catch the opponent offguard, especially if their character's edge attack has great reach (such as Donkey Kong's and Wolf's), and/or has invincibility frames (which are safer to punish an opponent caught charging smash attacks near the edge with than other edge options).
List of edge attacks