I'm not sure about blight, but the middle pic your foliage on tomatoes and zucchini looks like you have spider mites, but it's hard to see if there's any tip webbing. Are you noticing any webbing or any insects on the under leaves?

Looks like you're growing on a balcony so air circulation shouldn't be a problem. In the future I would definitely grow them in a bigger pot, looks overcrowded and probably pot bound, stressed out and now getting sicker. If it's not producing any zucchini or even trying to set flowers, thrash it!

Dude I just saw you posted this Aug. 7, so you have probably trashed them already.

Yup the zucchini and squash were trashed...replanted from scratch (new containers, soul, etc). Planted a lot less since every seed sprouted last time. The tomato plant you noticed in the background is actually doing good and yielding a good amount of cherry tomatoes. Whatever happened to my zucchini was isolated which is great news.