How are you avoiding getting the Bonus Challenge? Is it all luck-based? It's speed-dependant. If Yoshi travels full speed into a Goal Ring, it'll always end on the bottom left Flower Pedal (Bonus Challenge). To avoid this, spit an enemy out while holding forward as you jump into the Goal Ring. You lose the same amount of speed every time if done at the same spot. Thus, lose just enough speed to have the Goal Ring land on the blank dot after the bottom left dot. What do you need for 100%? Every level requires finishing with maximum stars (30), to reward not getting hit (Getting hit loses Baby Mario. You lose 1 star per second until retrieved); 20 red coins (Most are hidden amongst common coins. They make a chime when collected. There's a "final red coin chime" when the 20th is collected); and 5 Flowers (They're hidden throughout levels, usually behind an obsticle or annoying enemy). After you've scored 100% in all levels in a world, the Extra levels are unlocked (There's 6 total). These also require 100% score. So, 100% on all 54 levels. What do red eggs do? Red Eggs spawn 2 stars from inside the egg once it's cracked open. Eggs crack by colliding with an enemy, flower, or interactable object (ex: helpbox, floating "?" clouds). 30 stars are required to 100% any level.