It is unknown when or where Daniel got or caught Sylveon. She was confirmed to be female when she fell in love with Crystal's Vaporeon, but Vaporeon wasn't interested in her. Team Rocket watched from the shadows and decided to capture Sylveon, Eve, and Vaporeon for their boss. A net fell on Sylveon, Eve, and Vaporeon and pulled them up. Gabe demanded to know what was going on. Jessie and James revealed themselves and told the trainers what they were planning on doing with Daniel's Sylveon, Crystal's Vaporeon, and Gabe's Espeon, Eve. This angered Daniel threw out his Froakie who evolved into Frogadier. Team Rocket attempted to catch Frogadier, but it dodged their attacks and helped its trainer break the net that was holding Vaporeon, Eve, and Sylveon. Frogadier then helped its trainer blast off Team Rocket. Daniel then introduced the gang to his Pokemon: Zorua, Purrloin, Dedenne, and Raichu.
Sylveon is a very sweet Pokemon. She falls in love with any Eeveelution except female ones being female herself. She has a crush on Crystal's Vaporeon.