- You can play Bellelba & Brycen-Man as long as there's at least 1 card in either player's deck. It can also be played by discarding 3 cards from your hand if at least 1 player has more than 3 Benched Pokemon. But if at least 1 player doesn't have more than 3 Benched Pokemon, you cannot discard cards from your hand.
Source:
Cosmic Eclipse FAQ (2019-10-18), TPCi Rules Team (2019-10-31)