Use the following trick get permanent Digimon such as Paildramon or Omnimon. For example, to get Paildramon permanently you must have a Digimon that can digivolve to Exveemon and Stingmon at level 5. To get Omnimon as well you must have a Digimon that can digivolve to Metalgarurumon and Wargreymon at level 40.