I like every episode of Gravity Falls lol And they're not unimportant episodes by any stretch, so I'm not sure whose saying that!



Tourist Trapped introduces us to the characters and we see the things that make them tick. We get a cursory glance at them that sets the scene for their development later on.



Legend of the Gobblewonker is important because it introduces us to McGucket. At the beginning it may seem that a crazy old hillbilly making robots is a big goofy joke but it's actually so important later on for what will happen and what has already happened in the past. Plus if you're into G4G this is the first instance and a literal goldmine episode for evidence supporting the theory.



Headhunters is the first instance of Stan Twin theory and Stan's behaviour around Wax Stan - which at first seems comically over the top, as with McGucket - is actually very deep and pretty sad when the theory was later confirmed and we learn about Stan and Ford's past.



Anyone who says these eps aren't important or plot heavy need to rewatch them and read some theories and discussions.