Honestly I wouldn’t recommend skipping anything b/c I’m pretty sure every episode has some form of foreshadowing in it. But, if you really want to skip certain episodes then the ones without major foreshadowing and plot are: Together Breakfast, Frybo, Cat Fingers, Tiger Millionaire, Arcade Mania, Onion Trade, Beach Party, Joking Victim. Once you reach the Lapis Lazuli episodes pretty much every episode form there on out is packed with foreshadowing and important worldbuilding and plot. I REALLY would not suggest you skip any episodes but if you must, the ones I listed can be skipped without loss of major detail.