Nintendo has announced that there will be a Halloween Special Battle taking place in Super Mario Bros. 35. It begins on October 30th and will conclude on November 2nd. The official UK Super Mario Twitter account made an announcement tweet about the matter, so you can see it down below.

Original source: https://mynintendonews.com/2020/10/29/a-halloween-special-battle-is-taking-place-in-super-mario-bros-35-this-weekend/