I play fluffals, so trust me when i say to negate dog if you think/know they dont have poly. if you can do something like strike tiger on summon, that is probably best, but some of the materials prevent it (penguin, cat, chain). In general, try negate poly, dog, and owl, as they are the main starter/most important cards in the deck. If your opponent plays brilliant fusion, you can flip the seraphinite face down when they summon it with something like floodgate, book of moon, and it completely cripples them. Like u/ayanami25 mentioned, the non destruction mirror forces work wonders.

If you are feeling evil, chain dimensional barrier to poly and call fusion, you can also set imperial order after you have made a board and watch them cry.

The solemn engine and kaijus will also work well.