I'll try that Hawchula set definitely. Never liked the Hi Jump Kick's recoil if you miss.
Stockpile is pretty useful, however I see where you are coming from. Also in regards to Shadow Ball, I was thinking of using Focus
Miss Blast, however Shadow Ball seems to be covering more bases, especially opposing MGardes, ghosts and psychics.
The other problem I see with Shadow Ball is that Hyper Voice already rips through the aforementioned types you mentioned. Ex:
232 SpA Pixilate Mega Gardevoir Hyper Voice vs. 252 HP / 24 SpD Slowbro: 264-312 (67 - 79.1%) -- guaranteed 2HKO after Leftovers recovery
232 SpA Mega Gardevoir Shadow Ball vs. 252 HP / 24 SpD Slowbro: 242-286 (61.4 - 72.5%) -- guaranteed 2HKO after Leftovers recovery
232 SpA Pixilate Mega Gardevoir Hyper Voice vs. 0 HP / 0 SpD Mega Gardevoir: 175-207 (63.1 - 74.7%) -- guaranteed 2HKO
232 SpA Mega Gardevoir Shadow Ball vs. 0 HP / 0 SpD Mega Gardevoir: 160-190 (57.7 - 68.5%) -- guaranteed 2HKO
In other words, a neutral Pixilated Hyper Voice actually outdamages a 2x super effective Shadow Ball. That's another reason why it's not that necessary anymore.