i recommend doing it on the first go since ark gets incredibly difficult on loops, all of blue room and most of mines can be done with brother bobby alone, just about 80% of every other attacking baby is useless in comparison since they're too expensive and not cost effective except for: lil loki, harlequin baby, spike baby (for isaac's fork synergy) and deserter, peeping might be good now since the rework but i have yet to try him out; as for items be on the lookout for: isaac's fork, sanguine bond, frosty mint, black/brown bean, present (for the chance to get imp since it's the only way to get it) and safety blanket; as for active items try to get a run with either kidney bean, blue candle, glowing hourglass, telepathy for dummies or monster manual, sacrificial altar can be pretty powerful too but so would moving box, but if you ask me i'd say the go to actives are glowing hourglass and kidney bean, with glowing hourglass you can counter the mom hands and with kidney bean you can charm the frosties to fight on your side for basically the rest of the level.