- Return
- Mega Punch
- Dizzy Punch
- Strength
- Facade
- Retaliate
- Giga Impact
- Frustration
Return and Frustration
Return and Frustration are Kangaskhan's most powerful STAB. You may use them more than the others, because 20 PP / 102 BP (153 STAB) is immense. Now, if for you, it is easier to make Kangaskhan's happiness high, go for Return. If it is easier to make it hate you, Frustration is your deal. Although I think Frustration is much funnier and harder to get than Return.
Mega Punch
120 STABbed and 85 Accuracy is just not that great. Dish in 20 PP and it become a little bit better, but widely inferior to Return and Frustration in term of Power / Accuracy, and no effects is not cheering you to take it. Now, if you just cannot make Kangaskhan love or hate you and the 85 % accuracy is not bad for you, then go ahead.
Dizzy Punch
105 STABbed and 100 Accuracy is pretty nice. Now, it only has 10 PP. Not very cheering. But it gets to confuse opponent with a 20 % chances on doing so. So it is at least better than Mega Punch.
Strength
120 Power when STAB and 100 Accuracy, 15 PP, no effects. Inferior to Dizzy Punch but superior to Mega Punch. If you prefer PP and accuracy, and cannot make Kangaskhan love or hate you, it is a good choice. In-game, I would go for it. But competitively, go for Return.
Facade
105 STABbed (210 when Paralyzed or Poisoned; Burning stays 105 except for Guts) and 100 Accuracy is OK. 20 PP, no effects. So, inferior to Dizzy Punch and to Strength but still better than Mega Punch. Now, why this over something else ? If you have Skill Swap on Espeon, you can make it wonderful: Skill Swap to Gliscor, then Espeon gets Poison Heal. Then, switch Gliscor to Kangaskhan and use Skill Swap: Kangaskhan @ Poison Heal. @ Toxic Orb. @ Facade. *Are you fucking kidding me ?**
Retaliate
Not the exact best choice, just a sole option. I would even prefer Mega Punch to this. But if Kangaskhan is your Revenge Killer, then this must be a decent option. 105 (210 with effect) STABbed and 5 PP is OK. But I would not use this.
Giga Impact
You are crazy and thirsty of power ? You want an ultimate 225 STABbed move with a recharge turn, 5 PP and 90 % of accuracy ? You really want to make a use of this ?? Mega Punch is better. This is simply crazy. In-game, it wrecks havoc and you can switch. But not competitively.
You can also use Fake Out. Not being the exact powerful move, it still has a great effect. Hope I helped !