Season 9

Season 9 of GO Battle League lasted from August, 2021 to November , 2021. It is preceded by Season 8 and succeeded by Season 10. This GO Battle League Season ran concurrently with Season of Mischief.

In this Season, Little Jungle Cup was introduced. GO Battle Night has become GO Battle Day to allow more Trainers participating.

Formats
Great League Remix: 1,500 CP limit. Top 20 Pokémon banned.

Ultra League Remix: 2,500 CP limit. Top 10 Pokémon banned.

Little Jungle Cup: 500 CP limit. Only Normal-, Grass-, Electric-, Poison-, Ground-, Flying-, Bug-, and Dark-types allowed. Shuckle and Smeargle banned.

Halloween Cup: Only Poison-, Ghost-, Bug-, Dark-, and Fairy-type Pokémon allowed, excluding Legendary and Mythical ones. 1,500 CP limit.

Kanto Cup: Only Pokémon with a Pokédex number between #001 and #151 allowed. 1,500 CP limit.

Rewards
Basic Premium
 * Rank 5: Mysterious Item
 * Rank 10: 750 (Basic) / 1500 (Premium) Stardust
 * Rank 15: 1 (Basic) / 2 (Premium) Rare Candy
 * Rank 19: Pokémon Encounter
 * Other ranks:

Stardust

The random items can include:
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Reaching rank 19 awarded:

Reaching Ace rank and above awarded avatar items and an avatar pose inspired by Leon from Pokémon Sword and Shield.

Pokémon
Guaranteed first Pokémon encounters:
 * Charizard: rank 1 (one only)
 * Mienfoo: rank 6
 * Noibat: Veteran rank
 * Deino: Expert rank
 * Pikachu Libre: Legend rank (one only)

Tier 5 Raid Bosses could be obtained starting at rank 20 during their time in raids.

End-of-Season rewards

 * (rank 19 or above)

September, 2021
The first GO Battle Day took place on September, 2021 from 12 a.m. to 11:59 p.m. local time. Ultra League and Ultra League Remix were available during this GO Battle Day.

November, 2021
GO Battle Day took place on November, 2021 from 12 a.m. to 11:59 p.m. local time. Ultra League and Ultra Premier Classic and Halloween Cup were available during this GO Battle Day.

November, 2021
GO Battle Day took place on November, 2021 from 12 p.m. to 11:59 p.m. local time. Master League, Master Premier Classic and Kanto Cup were available during this GO Battle Day.

Attack updates
These Attack updates went live at the start of the Season:

Attack changes

 * Weather Ball: Base power was reduced from 60 to 55 in Trainer Battles and Gym and Raid Battles.
 * Crunch: 30% chance to lower the opponent's Defense by 1 stage in Trainer Battles.
 * Zap Cannon: 100% chance to lower the opponent's Attack by 1 stage in Trainer Battles.
 * Scald: Energy cost decreased from 60 to 50 and 30% chance to lower the opponent's Attack by 1 stage in Trainer Battles.
 * Feather Dance: Energy cost increased from 45 to 50 in Trainer Battles.
 * Megahorn: Base power increased from 100 to 110 in Trainer Battles.

Attack availability
Some Pokémon received new Attacks to their standard Attack pools:

Trivia

 * The choice of Kanto Cup was voted by players.