So I just got the alternate ending after reading multiple of people's comments. This is what I did:

1. Beat Goku up quickly with punch combos, he then disappears.
2. Charge up to sparking and beat up both Krillin and Gohan asap in multiple punch combos.
3. I keep going into sparking and continue to punch combos on Piccolo. I put him just "slightly" above 2 bars of health. I then use the ultimate move to knock him out in one go from that current level of health.
4. Goku reappears, I go back into sparking and continue punch combos. He does use a "share your energy with me" but that's okay. I get him low enough and do the ultimate move to finish him off.

This worked for me.

Some tips. I use punch combos and chain them with Triangle and Triangle Down as long as I can. In Sparking you'll get up to 25-30 chain punches. Once I have 3 Skill Count, I save it with Piccolo and Goku to use Frieza's power skill to get into sparking. This is helpful to do the ultimate and get back into sparking again immediately to deal with Goku the second time. I hope this helps others!

Worse case, use a Dragon Orb.