I'm in florida, so it might be different for you, but one suggestion is to not jump from solo cups to bigger pots. If it's not an issue, put them into 1gal containers so that there's not a lot of excess moisture. Peppers in my experience spread their roots in search for water when the soil gets close to bone dry, which doesn't happen on the outer space of larger pots and smaller plants. unless it's hot out.
Re the wrinkling, it could be thrips and i think thrips is a virus? Is there any silk pulling the leaves together? Could be little worms making homes and moving on. Either that or did you just put them outside recently from being inside? I've noticed that can cause wrinkly leaves as well