honestly, i dont know where to start. So lets get down to basics.
1. plant roots need water but they also need lots and lots of air. when you over water a plany you are basically sufficating it and thats why it wilts. it isnt actually sufficating.. but you get the jist.
2. plant roots are also susceptable to all kinds of disease and bugs. root aphids are quite common (especially amoung those that reuse pots without sterilizing and have non-sealed grow rooms)
3. transplanting plants doesnt hurt them, when a plant root is damaged it actually triggers the release of hormones that increae root growth. that is why you shake a plants roots and loosen up the dirt when you transplant.
4. having a solo cup with no bottom and transplanting that directly into another pot is just about the dumbest thing i have heard in a couple weeks. Not going to get into why, it just is.
5. if you have a problem then you need to figure out WTF is going on, not just hope for the best and carry on.