*didn't read thread*
1. When Delia mentions Ash's father in the second episode, that is an American dub addition. That was not said in the Japanese version. In fact, Ash's dad has never been mentioned once in the Japanese version.
2. I know someone will bring up Giovanni. This rumour started with that whole live broadway show thingy 4Kids ran where the revelation of the show was that Giovanni was Ash's daddy. Once again, an American addition.
3. In the manga, Ash's dad is mentioned. He was a traveler who came into Delia's lodge or something, and then left. *cough cough* Both the dad and Ash's grandpa were Pokemon trainers. That is the ONLY. OFFICIAL. ASH'S. DAD. PROOF.
4. In the Pokemon 3 commentary, 4Kids says the Japanese will reveal who Ash's dad is in the next season, which was a couple of seasons ago and never happened. They may do it someday.
Ash's dad is probably someone who has never been introduced on the show, and is most likely not an existing character.