Challenge #6 is not that hard but it can trick you a bit: You do the following:
1. Activate Obedience Shooled (while you control no monsters of course) and Special Summoned the 3 listed monsters in Attack Positon.
2.Tribute Summon Green Baboon in Attack Position by offering Rodenut and Uniflora.
3.Enter Battle Phase and attack with Nimble Musasabi vs Sonic Duck, then activate Yellow Baboon's effect to Special Summon it from your hand in Attack Position (it doesn't matter what monsters you banish)
4. Activate Nimble's effect to Special Summon 2 more to your opponent's field.
5. Attack both Nimbles with Green and Yellow Baboons.
6. You win
So "their effects are negated" from obedience schooled doesn't work on nimble's dying skill, but does work on its "this card cannot be tributed for a tribute summon" for some reason?
Yeah because Nimble's effect activates in the Graveyard. Even if say Skill Drain was activate, it'll still trigger because it's no longer on the field. Same with Obedience Schooled.