Hello. I live in PA near Pittsburgh. The weather this year has been so so with tons of rain and ten temp changes. I went out today to water and check on my plants and noticed that some of pepper plants look terrible. Not growing well loosing leaves etc. yet some are thriving as well as my tomato plants. I am curious as to if you have any ideas as to why this is or what I can do to fix them?

Well, it looks as if something is eating them. Have you checked for critters?

Yep !!!
Some chewing critter. I'd spray them with something. And also put out some snail pellets.
😎😎😎

While all the rain might be conducive to snail activity, there's no reason to turn the garden into a chemical war zone, when the solution might be as simple as going out early in the morning with a bucket with an inch of water in the bottom....
If its a snail, or slug, they dont run away... They're easily caught, and chickens love them....

On the other hand....
I have seen pepper plants get sick from too much rain...
If the sun comes out, maybe they might get better.... If they caught a virus, there's no amount of toxic chemical poisons that will make a difference.

And....
Isn't the point of growing our own food to get away from dangerous biocides?

Incidentally, a saucer of beer is state of the art for snails and slugs.
You might want to cover the saucer with a plate, leaving a stick or something (to prop up the plate), to leave room for the critters to get in....

And...
If you're like me, no alcohol in the house.... A bit of yeast dissolved in the bowl of water is supposed to also be effective.