Solo is a single-player game mode in both Super Smash Flash (called 1-P Mode back then) and Super Smash Flash 2 (under its current name) that includes several games designed specifically for one player, such as campaigns to defeat a series of computer-controlled opponents, participating of events that have specific goals to clear, mini-game to test the player, etc. Players are awarded with numerous rewards and other collectibles by clearing single-player modes.
In Super Smash Flash
In the original, 1-P Mode features three game modes available for the player. On Classic mode, players get through a series of different stages, battling computer-controlled opponents, similarly Adventure mode, players have to traverse different levels filled with enemies and different tasks, both modes also present special bonus games. Players can also unlock All-Star mode to battle every playable character in the game with a limited amount of recovery items. Players can also participate on other mini-games such as Target Test and Multi-Man Melee. There is also a Training mode so players can practice with their favorite characters.
In Super Smash Flash 2
There are several new games and additions for the reboot. Classic mode returns mostly unchanged with a bit more levels. There are also event matches which are specialized matches that have a unique task and require certain requirements to be cleared. Aside Target Smash, players can also play Home-Run Contest, where the goal is to launch the Sandbag as far away as possible with a Home-Run Bat, attacking beforehand the Sandbag to give it extra damage so that it can be sent further away. There are several modes that are confirmed but are yet to be implemented.