@VG: What advantage will be gained though? The non mulligan player still has to go 2nd to use the RC or the BTS. If you win the flip, you go 1st (unless the oppo plays sableye). The flip happens AFTER both set up. So, even if the player is "one card away", depending on the flip, whether a player plays sableye, a trainer lock ie gastly or spiritomb makes a world of difference.
Simply knowing the oppo HAS a mulligan doesnt give you a great advantage. You wont SEE what he is playing until you place a basic face down, then look at oppo's hand to verify mulligan. The player will still have to elect the "safe" route or the gambling route. It is a player's choice. By laying down an ILLEGAL choice to feign a basic and not reveal a mulligan decision AFFECTS the other player too! They BELEIVE you are indicating a basic and are ready to go. That isnt true. The rules state the player has the right to now if the oppo mulligans DURING their set up. Again, ANY deck can mulligan, whether you are playng SP, stage 2, stage 1, theme deck, etc.
The rules clearly state the player must lay down a basic or fossil in the active position. IF you lay anything else down, you have a minimum of a game state error. IMO, you have intentionally mislead your oppo and as such, can be subject to the "dubious game action" section. Why go there when we have rules in place on how to set up and play?? Seriously folks, maybe too many of you are playing Poker and are into the "I know more than you" "I dont want you to have any info about my hand" era. It is a GAME. There is supposed to be SotG. Why are you pulling shenanigans?? It is a pure angle shoot to lay down a false basic. Simple as that. Call a spade a spade.
Keith
EDIT: There will be no staring contest bc the judge will ask why you havent set up. If players tell me they are waiting for the other to declare something and the nearly 2 mins for set up has been exhausted....there will be penalties. Are you here to play Pokemon or to have a staring contest??? Seriously. Just ask your oppo if he/she is ready to declare basic choice or mulligan. I'm playing my deck. I will make the choice that is best suited to my opening hand irregardless of my oppo's choice. If I can go off with an early RC/BTS Machamp, I will go that route (thats the way the deck is built silly, to chew up basics!) Same with other decks.