Palworld

I figured out a way to "easily" get them in single-player.

Recommended prerequisites (Not so easy):

• Reach level 44, for Legendary sphere's
• Upgrade your Capture Power to level 10 at the statue of power with Lifmunk Effigy's

Cheese method for Alpha Frostallion:

• Install one of following mods:

  • Pal Info
    https://www.nexusmods.com/palworld/mods/178
    I've been using this one up till now.
  • Pal Analyzer
    https://www.nexusmods.com/palworld/mods/336
    I will soon switch to this one, since it looks nicer.

  They both will show you the passive skills a pal has,
  allowing you to check em out before catching the pals,
  so you don't waste sphere's

• Travel to Frostallion,
  check his passive skills without battling,
  if they're not as desired, exit / re-enter your world,
  that will re-spawn / re-roll in a new one with new passive skills, repeat till you find a desired one.

• Start battling as soon as you find a desired one,
  took me 20-30 minutes for mine.

• There will be a large / tall ice rock in the area
  (Coordinates X: -349, Y: 519),
  just start circling around it,
  always keep the large / tall ice rock between you and Frostallion

• Eventually he'll climb up the ice rock,
  and will fall down from it eventually as well,
  which will hurt him through fall damage for about 300 - 3000 HP!

• Rinse and repeat until his HP is low,
  then start throwing your legendary sphere's 😄