Unused content (SSB4)
The following features are beta elements from Super Smash Bros. 4.
Gameplay differences
As of now there aren't many differences to mention, although some features such as stale-move negation weren't in earlier demo versions of Super Smash Bros. 4. The most notable differences are the menu's that gone trough some notable changes. In the first trailer of the game, Link can be seen with his old dash attack, which has since been changed. In the E3 Demo of Super Smash Bros. for Nintendo 3DS, an unused custom down special move for Kirby called "Hammer Bash" can be found, however, it does not appear in the final game. Ike's Eruption originally had red flames; in the final game, however, it has blue flames.
Note that the names under the character selection slots aren't present in the final versions of Super Smash Bros. for Nintendo 3DS.
Scrapped elements
A trophy for the Fire Emblem: Awakening character of Tharja was initially planned for the game, and the trophy was visible in leaked ESRB footage. Following the release of the game in Japan, however, Tharja's trophy was not found by players on Twitch, and later hacking showed that there was no data for the trophy in the final game, suggesting that it was removed some time after the ESRB footage. The reason for the removal of Tharja's trophy is considered to be related to the game's rating; her outfit as a Dark Mage was likely considered too suggestive for Smash 4's intended E10+ rating, compared to Fire Emblem: Awakening's T rating.
Planned characters
The Ice Climbers were originally planned to return as characters, with them fully functioning on the Wii U version, but technical limitations on the 3DS prevented their inclusion. They do, however, make a cameo as a trophy. Chrom was also considered before development began, but Masahiro Sakurai later decided against it in favor of Robin, when he saw that Chrom would end up another plain swordsman made redundant by Marth and Ike, while Robin provided a plethora of unique moveset options. He instead appears as part of Robin's Final Smash.