first they pointed me to a page on their site, but this page did not give any detail about any game other than classic bj. and indeed it says that it did not apply equally to the other 21 variants. that page said the number of decks for blackjack is 6. i wrote back saying the page they directed me to did not include the numbers for 21 variants and also red dog or war, so they responded to tell me that:
blackjack = 6 decks
other 21 games = likely also 6 decks, except
pontoon = 1 deck
table poker variants = (goes without saying) 1 deck
red dog and war = likely also 1 deck
so the only game they could say with certainty about was pontoon using one deck. the other games i asked about were met with the conjectural responses listed above. and contrary to normal bj, single-deck pontoon is worse for the player than multi-deck, as 5-carders are less likely and tying the dealer's hand more likely. i would hazard that single-deck red dog and war are also less favourable (though i don't know how many decks is the standard elsewhere) because the big payouts for three of a kind or a tie after a war are less likely to occur than with multiple decks.