Okay so far we have seen 8 people join the straw hats with common things : A fight involving the to-be member on their side. However Jimbei was an exception. And im guessing so will Katakuri. Katakuri , during his fight, admired Luffy's skills of staying up. Im guessing he was scared of Luffy due to his sudden awakening of future sight. But they fought and were on almost equal terms. In the end he grins to Brulee, who just says that she understands. Also pudding. Pudding has split personality and is literally torn over her feelings for sanji. Could she and Katakuri join the Straw Hats?