WTF is this? Ichigo has already defeated characters stronger than them due to him being the over powered hero, which I'll give me -1 as he's clearly going to always win.
First Mask: Sexta
Second Mask: Possibly Cuotro. Hard to quantify really. V2 Bankai Ichigo's only feats were striking down R1 Yammy (the Cero Espada) and causing him to fall, although Yammy tanked the Getsuga Tensho regardless. Then, he was able to deliver a moderate wound to Aizen, which is pretty impressive, even considering that Aizen barely reacted to Ichigo popping out of nowhere in front of him. Then he was able to fully dodge Gin's Bankai: Buto Renjin as it was coming at him from close-range.
This is all going off of the reiatsu basis for ranking and if his mindset is stable.
Exactly no one.
Plot always helps Ichigo. That old man was two chapters of internal trainer from getting his ass raped like Aizen.
This god like guy is just there to look pretty featless so far, but if it came done to it Ichigo would magically have some new power that would allow him to match him in power.