Area Zero Underdepths - Pokémon Rulings Compendium

What happens if I use Area Zero Underdepths to replace Sky Field, or vice versa? Does either player need to discard Pokemon because the Sky Field/Area Zero Underdepths stadium left play, or is the transition instantaneous?: As long as you meet the required criteria of the new stadium you would not have to discard any Benched Pokemon since one stadium's effect is replacing the other simultaneously.

Source: TPCi Rules Team (2024-09-26)

I have Area Zero Underdepths in play, a Tera Pokemon-ex as my Active Pokemon, and 8 Pokemon on my Bench, none of which have the Tera Trait. My Opponent uses an attack that allows them to Knock Out my Active Tera Pokemon-ex and also two of my Benched Pokemon. Once my Tera Pokemon-ex has been Knocked Out and discarded, am I able to discard my two Benched Pokemon that have taken full damage before I count them as KO'd, or do I have to KO them first?: You have to KO them first and your opponent gets to take Prize cards for them. After they have been KO'd, you would then discard one final Pokemon from the bench due to Area Zero Underdepths and then choose a new Active Pokemon.

Source: Stellar Crown FAQ; TPCi Rules Team (2024-09-12)

If I use Falinks' "Form Ranks" attack while Area Zero Underdepths stadium is in play and I already have 4 non-Tera Pokemon on my Bench, how many Pokemon can I put on the Bench if the first one I place is a Tera Pokemon?: Only one. Since there were no Tera Pokemon in play when the attack was used, there is only one space available to fill on the Bench.

Source: Stellar Crown FAQ; TPCi Rules Team (2024-09-12)