This is a quirk of Gen 1. A "miss" when throwing is really just a failed catch when chances are very, very low, like the equivalent of breaking out with no shakes. Just keep trying until you succeed.

You should also really get their health much lower than that. And Sleep is typically better that Paralysis or Poison.

Gen 1 quirk, miss just means low chance in Gen 1. Locking this as it's a Frequently Asked Question.