Ignoring defence

Iirc, Only Chaos Pink Bean requires more than 100% PDR Ignore, at 180% I think.

no, since %ignore ignores a percentage of their defense, so if you ignore 100% of CPB's defense, you're ignoring all 180%. this is why the more def a boss has, the more effective ignore becomes, because it ignores larger chunks of defense.

Ah learned something new, thanks for explaining!
Is there a list of bosses and how much physical resist they have?

And one more question, going over 100% PDR ignore is useless right?

you can use extractions or look for them in maplearchive, afaik P.Resist is always 50%, while P.Defense is variable and it's what PDR ignores.