Since Mecha Moon was in the 2016 version, it gets a secret level, which is unlocked after beating all of the previous secret levels. Ultimate's Mecha Moon is a pretty big departure from the original version of the level, so Moon Secret sticks very closely to it instead. The main gimmick here are Gravity Zones (which tbh I need to make look better). The green up arrow ones are low gravity areas, while the red down arrow ones are high gravity areas.
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.