Pokémon Masters EX will hold its next High Score Event around November, with Electric-type and Ground-type Sync Pairs set to be the recommended choices for the upcoming challenge. Players are encouraged to strengthen their Electric and Ground Sync Pairs ahead of the event, which will test teams built around the featured types. The announcement was published Sept. 8 at 11 p.m. PT, although the event period and featured content remain subject to change without notice.
Source: Official Pokémon Masters EX site