Worlds 4, 5, and 6

Custom Levels in World 4:
W4-1: Showcase 1-2
W4-2: Pleasant Pastures
W4-3: Prehistoric Plains
W4-4: Showcase 25-2
Boss: Larry Koopa

Custom Levels in World 5:
W5-1: Showcase 5-3 (originally slated to be in World 3)
W5-2: Showcase 38-3
W5-3: Blue Spectrum Bounty
Boss: Morton Koopa Jr.

Custom Levels in World 6:
W6-1: Lakitu Glacier
W6-2: Icy Terrain
W6-3: Sunshine Slopes
W6-F: Irregular Fortress
Boss: Lemmy Koopa