The Super Smash Bros. for Wii U version of Classic Mode is set up as a tournament with elimination style gameplay which lasts seven rounds. For the first time in the series, Classic Mode can be challenged by two players.
Like in the Classic Mode of Super Smash Bros. for Nintendo 3DS, the player begins with two stocks for each battle regardless of difficulty. The intensity meter is used to set the difficulty, with higher difficulties costing more Coins and offering better rewards. Losing and choosing to continue when the difficulty is above 2.0 costs some of the accumulated prizes and drops the difficulty by .5, also taking away some of the invested Gold to reflect the new difficulty. The prize roulette wheel is also shared with the 3DS version, with the addition of passes for Crazy Orders as potential prizes.
The mode is set on a large playing field, whose background depends on the intensity chosen, becoming darker and fiercer with higher intensities:
- Intensity 0.0 - 1.9: Water/Ocean Background
- Intensity 2.0 - 3.9: Grass/Plain Background
- Intensity 4.0 - 5.9: Sand/Desert Background
- Intensity 6.0 - 7.9: Lava/Volcanic Background
- Intensity 8.0 - 9.0: Dark/Shadow Background
On the field, the player character and the opponents appear as trophies: the player, identified by a glowing red trophy base, can choose which group of opponents to fight by moving their character towards it. The stage where the battle will be fought is visible on the field under the opponents. After each round, the losers are forcibly ejected from the field until only the last few remain. Team battles can occur, in which the player must choose their teammates among the characters they have previously defeated (or by their teammates in a previous team battle). During all rounds, opponents may hold trophies, equipment, coins, or Crazy Orders Passes, identified by the respective icons on the enemy's trophy, which are obtained only if the carrier is defeated by the player or, in a team battle, by one of the player's teammates.
The first three rounds are fought against regular characters. At the beginning of each playthrough, a random opponent is designated as a rival: marked by a glowing blue trophy base, the rival gets stronger and drops greater prizes the longer the player holds off on confronting them. In most cases, the rival will remain on the board until the player finally defeats it, but in very rare cases, they can lose before the player can face them.
The fourth and fifth rounds are fought against characters equipped with custom special moves, marked by an alternate trophy with a black base and appearing in an alternate costume.
When the player chooses a battle in the first five rounds, one or more opponents might suddenly be replaced by an intruder, marked by a glowing yellow trophy base, even in a team battle. Intruders are always in a permanent Giant or Metal state, but are guaranteed to be carrying a prize of some kind for victory.
The sixth round is against a Fighting Mii Team composed of 20 members, which appear surrounding the player on the game board in a group of nine.
In the seventh and final round, the player faces Master Hand, and at higher intensities Master Hand with Crazy Hand and possibly Master Core. Unlike the Classic mode of the 3DS version, the player cannot choose to fight Master Hand alone if Crazy Hand and Master Core are available.
- Clearing Classic Mode on any difficulty with any character will give the player a trophy of the character used.
- By clearing Classic Mode with a character, their Alternate Colored Trophy can become available in the Trophy Shop.
- Clearing with any character on any difficulty will challenge the player to defeat Falco. Beating him will unlock him.
- Clearing with five or more characters will challenge the player to defeat Mr. Game & Watch. Beating him will unlock him.
- Clearing on intensity 5.5 or higher will challenge the player to fight Lucina. Beating her will unlock her.
- Clearing on intensity 2.0 or more with five or more characters will unlock the Master Hand trophy.
- Clearing as Yoshi will unlock the Yoshi masterpiece.
- Clearing without losing a stock will unlock the Dr. Kawashima trophy.
- Clearing without losing a stock as Little Mac will unlock the Title (Punch-Out!!) music.
- Clearing in 20 minutes or lower as Olimar will unlock the Mission Mode (Pikmin 3) music.
- Clearing on intensity 5.5 or higher will unlock the Master Core music.
- Clearing on intensity 5.5 or higher as Kirby will unlock the Kirby's Adventure masterpiece.
- Clearing on intensity 5.5 or higher without customisations as Wario will unlock the Full Steam Ahead (Spirit Tracks) music.
- Clearing on intensity 7.0 or higher with all characters will unlock the Regal Crown headgear.
- Clearing on intensity 8.0 with two or more characters will unlock the Master Fortress: First Wave music.
- Clearing on intensity 8.0 with three or more characters will unlock the Master Fortress: Second Wave music.
- Clearing on intensity 9.0 without customizations will unlock the Knuckle Joe trophy.
- Clearing on intensity 9.0 without losing a stock will unlock the Double Final Smasher Protection Badge equipment.
- Clearing on intensity 9.0 in 12 minutes or lower as Marth will unlock the Critical Hitter Sword equipment.
- This is the first Classic Mode where it is possible for any battle to be fought on a stage which is neither the home stage of any of the participants, nor a stage belonging to the Super Smash Bros. universe.
- During a team battle, if the player KOs a teammate (such as by setting off an explosive near them), they may receive a second trophy of that character after the battle. Both this and the first trophy can then be chosen as teammates, allowing duplicate characters in six- and eight-player team battles.