Blizzard hit the nail on the head when they decided to release Workshop for Overwatch as it is proving to be a source of endless creativity and fun. One of the latest exploits of the creators is Smashwatch, a mashup with Super Smash Bros.
Overwatch previously received a 2D mode through the magic of the Workshop, called Flappy Pharah. Those who don't like breaking their hardware out of flappy frustration might prefer beating up the opposing team in Smashwatch. The name is a mashup of Overwatch and Super Smash Bros., highlighting what the mode is about.
Initially, the match starts in first person, just like Overwatch but then the camera pans out to the side and provides the well-known Smash Bros. perspective.
Each hero has unique abilities, as you might expect, and the rules are pretty much the same as in Nintendo's brawler. Hitting the enemies increases their percentage which means they will be knocked back further by your attacks. Knocking an enemy off the platform or off the screen will eliminate them.
Recoveries and mid-air dodges are possible and individual shields are there, adding to Smashwatch's depth. Furthermore, everyone gets the double jump ability which might make Genji sad but the mechanic is necessary to faithfully recreate Super Smash Bros. series' combat.
Those who wish to try the mode out can do so by using VZ4YG code but we suggested watching the demonstration video first in order to understand the basics. It might be interesting to give this mode a go by plugging a gamepad into your PC for full SSB experience.
Workshop is not yet available on consoles but it should come along soonish, according to Jeff from the Overwatch team himself. Meanwhile, if you are looking for more custom modes, here is a list of in the Workshop.