Thundurus and Volcarona have been revealed from S5a Matchless Fighters, which release in Japan on March 19th. These cards will likely become part of our next main set following Battle Styles.
[R][C] Combustion: 50 damage.
[R][R][C] Fire Spin: 170 damage. Discard 2 Energy from this Pokemon.
Weakness: Water (x2)
[L] Assist Spark: 30 damage. You may attach a [L] from your hand to 1 of your Benched Pokemon.
[L][L][C] Thunder: 130 damage. This Pokemon does 30 damage to itself.
Weakness: Fighting (x2)