You may be looking for the fanon game, Super Smash Bros. Next. You can find it here.
Super Smash Bros. Next is the first game in the series to contain DLC. It's purchased using Smash Cash (SC), which is won by winning battles.
Each of these packs contains characters and/or stages.
Just Fooling Pack
This pack was released on April Fools' Day 2016, and contains 1 character and 4 stages. It costs 100 SC.
|Dr. Mario||The doctor is in the house! Dr. Mario is back, and he's got a new moveset to match.||
|PokeFloats||Pokemon||A returning stage from Melee, the PokeFloats fly over Kanto as you battle atop them.||Floats of several Pokemon.|
|Mushroom Gorge||Mario Kart||Face off on the Mushroom Gorge. It's easy to fall off here, though.||Racers and Bouncy Mushrooms.|
|Frozen Factory||Sonic the Hedgehog||Welcome to the col-err-casinos of Frozen Factory? Battle as you get hit by springs and get lucky on the slots.||Springs, Egg Pawns, and Slot Machines.|
|Flat Zone 2||Game and Watch||Mr. Game and Watch isn't here, but he left his home stage anyways.||Varies depending on game.|
Forgotten Heroes Pack
This pack contains 3 returning fighters from Melee. It was released on April 30th, 2016, and costs 100 SC.
|Pichu||The pre-evolution of Pikachu has returned. His moveset has been tweaked so that he's a balanced character, and not a weakling.||Thunder Storm|
|Mewtwo||Mewtwo, a clone of the Pokemon Mew, teleports into SSBN! It's inclusion in the game was well recieved.||Psystrike|
|Roy||The second of the original Smash Fire Emblem duo is back. Roy's swordsplay is admitingly better than Link's.||Limit Break|
- It was originally called the "Classic DLC", so the code that comes with the game is still usable.