Well they had to put in hardowork to fight Madara,and Kaguya.And their talent allowed them to use their new powers so well.
Eh, not really.
See what rikudo chakra did to kakashi -_- he was pretty much on Naruto and Sasukes level for those few mintues. Were't even his eyes.
No offense but I hope you don't truly believe there was hard work involved. Within 48hrs, Naruto's strongest form went from Sage Mode to Chakra mode, to Bijuu mode, to Bijuu Sage Mode, to Rikudo Naruto :|. He went through 4 different power ups in 2 days. Come on now Lol.
That's like Goku going super saiyan for the first time against Frieza, and then going super saiyan 4 as as soon as frieza goes 100% full power. That's why the story went to crap, all the morals of the story just thrown out of the window with the click of a finger. Give tenten rikudo chakra and she'll hold her own against juubi jins, hardwork my ass Lol.
Why was it so rushed? What happened to character development? Why did Naruto and Sasuke have to become gods so quickly at the age of 17, why not let them grow up a bit and improve even more to reach those levels. If Naruto gained his rikudo power up like around the time he became hoakge, then yeah cool. This was rubbish though.