From SmashWiki, the Super Smash Bros. wiki
Techniques is a sub menu of the Help menu in Super Smash Bros. Ultimate. This menu will provide a list of various techniques in the game on the left side of the screen, which can be sorted by Common techniques, Fighter-specific techniques, or All techniques using the L or R buttons. Highlighting a technique will give players information on that specific technique and a quick demonstration video on the right side of the screen.