Auntie Edna (home media; 5:07)
IMDb; Pixar; Pixar Wiki; TV Tropes; Wikipedia
streaming sites: Disney+
This is a bonus feature on the Incredibles 2 Blu-ray. I didn't have a Blu-ray player at the time it was released, but since the copy I have includes a digital code, I was able to watch it on Movies Anywhere. (This was before Disney+.)
The short shows what happens after Bob drops Jack-Jack off with Edna for one night. She observes a slew of the baby's powers, so she'll know how to make a super suit for him. It's a pretty simple story, but it's cute and amusing and cool.