One of the most frustrating and disingenuous forms of argument I’ve come across has to be the shotgun approach. This is where someone will begun just spewing arguments, other topics, contexts, anecdotes, and anything else they can, all as if it serves as some evidence, usually largely out of the scope of the original topic.
The best method I’ve found to overcome this is try to identify a shared concept, and go after that instead, something that at it’s root is the basis behind everything they’ve said, the foundation effectively of every single thing they’re trying to push, all at once.
But in the end, the way you deal with things needs to be very contextual, specific to the person your arguing against, and not every platform has the tools you may need to properly combat this tactic. Sometimes, it will be better to simply ignore them.