Difficulty is an option in some single player/co-op modes that allows a player to adjust the game after one's skill (allowing them to choose the mode to be on easy or hard games). In the most cases, there are five difficulty levels/books. Depending on what mode is being played, different difficulty levels/books will affect the game in different ways. For example, a higher difficulty level/book in the Subspace Emissary will make the enemies harder by giving them more HP and making their attacks stronger, while a higher difficulty level/book in Target Smash won't affect the characters' properties at all, but instead change the stage's design into a more difficult one. Sometimes, unlockables such as trophies or stickers depend on the difficulty on which a game mode is cleared. In the Subspace Emissary, Stock Balls vary in number, from appearing in most levels in Easy (the Easy game) to never appearing in Very Hard and Intense (Very Hard and Intense games)
In Smash 64, the difficulty setting is only available for the 1P Game. In the other three games, the setting appears for the Classic Mode, Adventure Mode/Subspace Emissary and All-Star Mode. Additionally, in Brawl, the setting is available for Boss Battles, and has been added to Event matches and Target Smash!!. However, the event matches in Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS/Wii U only have three difficulties (Easy, Normal, and Hard).
Difficulty levels in Super Smash Bros. and Super Smash Bros. Melee[]
- Very Easy (blue difficulty/blue book)
- Easy (green difficulty/green books)
- Normal (yellow difficulty/yellow books)
- Hard (orange difficulty/orange books)
- Very Hard (red difficulty/red books)
Difficulty levels in Brawl[]
Easy (やさしい, Easy)- Normal (ふつう, Normal)
- Hard (むずかしい, Hard)
- Very Hard (とてもむずかしい, Very Hard)
- Intense (ゲキむず, Extreme)
In Event Matches, only three difficulty levels are available: 
Easy (blue difficulty/blue book), 
Normal (green difficulty/green books), and 
Hard (yellow difficulty/yellow books).
Difficulty levels in Super Smash Bros. for Nintendo 3DS/Wii U[]
Difficulty levels were significantly overhauled in Super Smash Bros. for Nintendo 3DS/Wii U. The game's retooled Classic Mode features the Fiend's Scale to determine the game's difficulty. In this system, the player is able to select an intensity from 0.0 to 9.0, with higher intensities leading to harder fights, but more rewards; the default intensity is 2.0, and selecting other intensities requires some coins, with each .1 increment costing the player a set number of coins depending on the intensity.
Selecting an intensity lower than 2.0 also costs gold, with the amount increasing per decrement.
Nintendo 3DS Version[]
Wii U Version[]
| Intensity level | Numeric values | Cost per 0.1 increment |
|---|---|---|
| Effortless | 0.0 to 0.9 | minus 5 coins |
| Easy | 1.0 to 1.9 | minus 5 coins |
| Standard | 2.0 to 2.9 | 8 coins |
| Tougher | 3.0 to 3.9 | 12 coins |
| Challenging | 4.0 to 4.9 | 15 coins |
| Heatin' Up | 5.0 to 5.9 | 20 coins |
| Extra Spicy | 6.0 to 6.9 | 25 coins |
| Infernal | 7.0 to 7.9 | 45 coins |
| White Hot | 8.0 to 8.9 | 95 coins |
| Nothing Harder! | 9.0 | N/A |
The difficulty chosen - in addition to making the CPU opponents tougher and the prizes greater - determines what is faced at the end of the game, with higher intensities keeping what is fought in the lower, but adding a new foe to the mix. In the Wii U version, the encounter is as follows:
| Inclusion | Intensity range |
|---|---|
| Master Hand | All Intensities |
| Crazy Hand | 3.0 and Up |
| Master Edges & Master Shadow | 5.1 and Up |
| Master Beast | 6.0 and Up |
| Master Giant | 7.0 and Up |
| Master Fortress | 8.0 and Up |
Every time the player loses, he or she is given the option to continue. If the player elects to continue, the intensity lowers by 0.5. Regardless of whether or not the player continues, some rewards attained in the Classic Mode will be lost, as will some coins on the Fiend's Scale. The system is essentially identical to the Fiend's Cauldron intensity system from Masahiro Sakurai's previous game, Kid Icarus: Uprising, including the same titles.
On All-Star mode and Event Matches in Smash 4, they however use the traditional difficulties. But only three difficulties are available (Easy, Normal, and Hard). Unlike in Brawl, while Easy is the blue difficulty/blue book, the colors for Normal and Hard are the yellow and red difficulties/books respectively.