Can you use Stormy mountain to search the deck while having an Eternatus Vmax's ability Eternal Zone "live", "online" and an open bench space? I am assuming the game does not know if a duel type is printed that meets the requirements of being dark & light or dragon. Since there is not at the time of asking, it would allow a search and shuffle of the deck but would be failed in the end.
Stormy Mountain: Once during each player's turn, that player may search their deck for a Basic Lightning Pokemon or Basic Dragon Pokemon and put it onto their Bench. Then, that player shuffles their deck.
Eternatus Vmax, ability Eternal zone: If all of your Pokémon in play are Darkness type, you can have up to 8 Pokémon on your Bench and you can't put non-Darkness Pokémon into play. (If this Ability stops working, discard Pokémon from your Bench until you have 5.)
Stormy Mountain: Once during each player's turn, that player may search their deck for a Basic Lightning Pokemon or Basic Dragon Pokemon and put it onto their Bench. Then, that player shuffles their deck.
Eternatus Vmax, ability Eternal zone: If all of your Pokémon in play are Darkness type, you can have up to 8 Pokémon on your Bench and you can't put non-Darkness Pokémon into play. (If this Ability stops working, discard Pokémon from your Bench until you have 5.)