CuBots, also referred to as Cubots, are robotic creatures who were originally meant to appear in Super Smash Flash 2 as common enemies for Adventure Mode: The Flash Of Shadows. However, after the storyline was remade and the mode itself was scrapped, it was confirmed that they would be no longer be appearing in the game.
In the game mode's original story, CuBots were Umbra's main minions. They came in three different types, each with different attacks, although overall they shared the same role in the story. They were planned to appear as enemies in multiple levels throughout the game mode, including during the final boss fight against Umbra himself.
Although the CuBots had been a known feature of The Flash Of Shadows since the game mode's reveal, their original designs were not publicly revealed until April 2, 2020 following former developer FriendAlias's "Flash of Shadows" trailer, his proposal for McLeodGaming's April Fools' Day 2020 joke.
The CuBots were also redesigned by FriendAlias to be included in that trailer. This design for the CuBots is a mixture of the three CuBot types that existed previously.