There is no NU at tahe moment. Why would Kangaskan try to use Power-Up Punch on Fighting types anyway? It can use Power Up Punch on something it can hit for super effective damage to garner a Swords Dance while wearing it down or get a free +2 on the Pokemon switching in. Kangaskhan also learns Bulk Up, so it can use Drain Punch there, or use both on an all-out attacking set. There are a lot of possibilities for a powerful Pokemon that can attack twice (yes, I know the second hit is half damage, but it's still a very useful capability; a separate crit chance on both attacks, for example).
Not what I meant, exactly.
Yes, there isn't an NU as of now, but depending on where it ends up, it still has it's share of problems. Normal typing can be a blessing and a curse for it with how many Fighting types in general run rampant and with how priority is such a major part of the metagame, anything with Mach Punch or that generally outspeeds it can be a major threat to it.
I did a run of calcs of Choice Scarf Sawk VS Sub Punch Kangaskhan from the BW/2 meta and...
"Close Combat: 139.61 - 164.54%
Ice Punch: 29.36 - 34.62%
Stone Edge: 39.05 - 45.98%
Earthquake: 39.05 - 45.98%
252+ Atk Sawk Close Combat vs. 40 HP / 0 Def Kangaskhan: 504-594 (139.61 - 164.54%) -- guaranteed OHKO
(504, 510, 516, 522, 528, 534, 540, 546, 552, 558, 564, 570, 576, 582, 588, 594)"
As I said, it's a blessing and a curse to be a Normal type. Yes, the new generation may give Khan his boosts but it's still not going to have the edge it wants against fighting types unfortunately. It's easily forced out by Fighting types and unless it learns something like Zen Headbutt through breeding or Move Tutors, it's still going to have the problem of being out sped. Maybe it would be viable to run a Choice Scarf set but that defeats the purpose of running Power-Up Punch.
Mind you, I really do think Khan's getting a major boon this generation from this move and Parental Bond but it's glaring issues is going to need either major team support or some really good new moves. Maybe it learns a new Fairy move - Play Rough would be perfect.