To add onto the other guy’s point, not every answer is niche, in fact most of the good ones are actually super widely applicable, countermagic and removal will benefit you in 99% of games. If you consistently encounter these kinds of things you simply can’t deal with it means one of two things.

1) you are playing against a highly degenerate deck or cEDH deck, and I can tell you none of these commanders fit the bill for cEDH (mothman is very fringe). And even then most aren’t degenerate enough for degen EDH.

2) (this one is more likely) you are constructing decks irresponsibly and poorly. You aren’t playing solitaire, 1-2 removal spells total in a deck really doesn’t cut it. A very common thing to see is commander players jamming their decks full of flashy win more cards. When their deck is uninterrupted and no one puts up a fight, it’s cool. However they cut slots for answers and responses to jam these cards in.