Who is Ash's dad? I've heard suggestions like Oak, Giovanni, random travelling trainer and even (sickos) Ho-Oh, I personally think it's Giovanni, but I don't read the anime, so the answer might be there?

Well I think he hasn't met his father yet.

te could check Bulbapedia

But if he has met his father I think it'd be Giovanni but that would make Silver his brother...

If te ask me, I think Ash's dad will never be shown. This is because (if te want my thoughts) His fauther left on his pokemon journey. When he was in the arancia, arancio islands, he was the 'chosen one' to collect the treasures. Then, at thunder island, he got fried da Zapdoes *people stare* ........ dont ask. I just made that up now