That works too, but if you only use dodges to deal with them then you'll get nonchalant about it. Then you'll start tossing out rolls whenever you suspect Ness is going to PK Fire. From there it's not hard to bait the response after setting up the occasion, especially if you're near a ledge or something and don't want to get pinned by PK Fire. Just mix up how you work around them. Being mobile is usually the safest bet.
Does Bowser's crouch cancel not work against PK Fire? I haven't tested myself. But if you can at least crouch cancel it then you can dtilt to halt his approach from within the pillar or get your shield up and roll away. You could also time a fortress (which you did one time, not sure if that was accidental) but you'll face potentially less punishment if you are grounded when you start the fortress.
Indeed. <3 How quickly you got out of it was astonishing, made me reconsider my use of it. I have a much greater sense of patience when it comes to using it now, I don't always barge in blindly with a dash grab upon its activation. It's much better to just observe my opponent's reactions from an "empty" PK Fire and build my strategy for using it based on those.