It shouldn’t let the effect to happen before being discarded. I think that this is a bug.
● Put [Parallel City (BKT 145)] to Hand
● Mazeman has shuffled deck.
● Chaotic Swell (CEC 187) will be discarded as Parallel City (BKT 145) is played.
● Chaotic Swell (CEC 187) was discarded
● Parallel City: Any damage done by attacks from Mazeman’s [G], [R], or [W] Pokémon is reduced by 20 (before applying Weakness and Resistance).
● Parallel City: Dreamcast can’t have more than 3 Benched Pokémon.
● Emolga (TEU 46) was discarded
● Parallel City is now in play.
● Parallel City (BKT 145) was discarded