First off, in a melee character select screen, you can hold b and it will go back automatically.
second, there is a way to play as master hand in a melee or event match or to get a huge amount of KOs on cruel melee. i will explain it as best as i can(it can be done with 1 player or an easier method with 2 players or more).Btw, it helps if you do not have a lot of names or none at all.
1. first, go to any event where you can choose your character(this is the one player version, which is harder to do and harder to explain). make sure your controller is in the third player spot(only way to play as master hand). then go to the name list without selecting a character and scroll to the bottom of the list and press b once you've reached the bottom. then press on the name list again and hold b when you press the name list at the same time you open it. go down to create new name and press a while holding b(which usually cancels out and goes back a page of the menu).if done correctly, it will either go to the stage select screen or to the event or stadium match. you will then play as master hand(it is normal if your game pauses at the stage select screen, but will not do any harm to the gamecube or the disc) to attack with master hand, hold b,a,r,l, or z and press on any direction of the directional pad to do an attack(d-pad is under control stick)
2. this method to play as master hand is for 2 players or more and is much easier than doing it with one player. first, go to a 2player match. then on the third player slot, scroll down the name select to the create new name, but don't press it. then with the other controller in any other slot, go to the basck button at the top right of the character select screen, but choose a character you want to melee with first. then at the same time, press the back button on the screen and the create new name button at the same time. if done correctly, it should take you to the stage select screen or to a random match if your stage select is on random. it is just as common for the game to pause on this method as it is for one player and the attacks are just the same as when you face him in event match 50 or classic mode. If you go to a melee without it pausing, you should have the match, but it may pause after each match. it has happened to me every time.
btw, i did not find this cheat. a youtuber named exchord92. please subscribe to him for finding this awesome cheat. thanks(you cant subscribe to me anyway cause i dont have an account.