Interprets "gym battle" as the first Grand Trial.
Option 1: Encounter wild Pokemon or soft-reset your starter. Winds up being full odds either way.
Option 2: SOS Chains. Unlocks this feature after defeating the Totem Pokemon from Ilima's trial. Increases your odds of finding a shiny for every ten Pokemon in the chain. Is not entirely certain of the odds, due to conflicting information. Presumes the following to be correct:
0-10 chain length: 1/4096
11-20 chain length: 1/820
21-30 chain length: 1/455
31+ chain length: 1/315
(Might reset at 255 chain length.)
Other tips:
- Use an Adrenaline Orb during the battle. Increases the odds of the Pokemon calling for help.
- Improve your call rate further by using a Pokemon with Intimidate, Unnerve, or Pressure. Will be limited to Growlithe in Sun/Moon that early. Grabs Ekans in Ultra Sun/Moon too.
- Recommends fighting a Pokemon with a high call rate. Suggests Caterpie, Zubat, Pikipek, or Pichu. May or may not find these Pokemon good, however, due to possible things like Poison Sting and Static. Hurts to work around in an endurance battle.