First of all that one villain enemy Digimon is Dark Masters against The original DigiDestined is Daigo Nishijima's group many year ago when they was kids. In 1995 one villain enemy Digimon is Parrotmon against Greymon when Tai, Kari and another DigiDestined when they was little kids saw Parrotmon against Greymon. In 1999 five villain enemy and group is Devimon, Etemon, Myotismon, Dark Masters (return) and Apocalymon was against DigiDestined is Tai's group In 2000 one villain enemy Digimon is Diaboromon against Omnimon with Tai and Matt In 2002 three villain enemy Digimon and human is Digimon Emperor, Arukenimon & Mummymon, Yukio Oikawa and MaloMyotismon (return) against all DigiDestined is Davis' group, Tai's group, all Japanese, American, Chinese, Vietnamese, Indian, Australian, French, Mexican, Russian and Siberian DigiDestined. But in 2002 after Digimon Emperor there one villain enemy Digimon is Wendigomon against DigiDestinedis Davis's group and Willis. In 2003 one villain enemy Digimon is Armageddemon (return) against Omnimon, Angemon, Angewomon and Imperialdramon Paladin Mode with Tai, Matt, TK, Kari, Davis and Ken. After that all killed of evil villain enemy Digimon. In 2005 there one more villain enemy is Mysterious Man (Look like young Gennai from 2002) So how come that Mysterious Man has not show up before 1999 with Digimon Adventure Tai's group or 2002 with Digimon adventure Adventure 02 Davis's group. Also same thing that Willis has not show up in Digimon Advemture 02 Episode 40 and 50. Daigo Nishijima's group and Meiko Mochizuki has not show up in Digimon Adventure and Digimon Adventure 02. There one reason why are hide something not want show up and meet Tai's group or Davis's group from past between 1999 and 2002.