Along with the limited-time special bonuses for players, the event adds Devil Jin and Kunimitsu as unlockable characters.
Also, previously, they launched a "Mokujin Festival" event, giving players access to a limited-time "Mokujin Rush" mode, a version of the arcade mode where the enemies are all Mokujins that gave extra bonuses when defeated.
Source: Tekken Revolution Official Site, @Harada_TEKKEN (TwitLonger)