This is the final secret level in the game, unlocked by beating every previous level and having all of the trophies. The Super Freaks return to their stadium, where the Anti Freaks assemble this gauntlet of death.
Exciting Encore is basically the "Champion's Road" level, a super difficult level that's meant for those who have mastered the rest of the game. There are six sections, each based off of the main worlds of the game; so far the Normal World and Crazy World sections are in.
At this time, Mr. Freaks has 3,956 views for Super Mario Maker 2 spread across 67 videos. About 6 hours worth of Super Mario Maker 2 videos were uploaded to his channel, or 9.52% of the total watchable video on Mr. Freaks's YouTube channel.