Really been enjoying this game this so far, but I'm really lost on how to go about getting the special sizes for the characters other than Sally. I know with her you do it by eating the bosses from the bubblegum cake but given the bubblegum cake is exclusive to her, how do you trigger it for the other characters? Particularly with Martha I'd like to know. I know there's a charm in finding little secret mechanics like that but I think the game could benefit a lot from explaining that stuff a bit better, like the aforementioned special sizes and the alternate ways to defeat the bosses. Outside of that, the game has been phenomenal.
for Martha you need to press the burp button when the boss is low enough in health and the BP bar is not over 100%, for Bella same thing but using the BFB-9000 button, this should give you the achievment, for Phoebe I haven't had a chance to make it happen either it ends too soon or I lose to the boss.