I doubt Gouki finishes off Gouken. Gouki defeating Gouken or vice versa, is another story.
For one, Ryu never becomes Gouki's pet, nor do he and Ken seek revenge against Gouki in SFIII.
For another, Ryu knows the Shin Shoryuken (perfected version), Denjin Hadouken, and the Joudan Sokutou Geri by the time of SFIII; moves which are only demonstrated by Gouken prior to their usage by Ryu in SFIII.
__________________
"To all visitors from Transylvania looking for the head of Voivode Dracula: Yes, we have it. Yes, he's dead. No, you cannot see it. No, he will not return and invade you again. It has been over thirty years, please stop pestering us."
Actually, Ryu had the Shin Shoryuken and the Metsu Shoryuken prior to SF4. He had them both in Alpha 3.
also, on the Oro vs Akuma thing, I don't beleive Oro can win that fight, and the paraphrasing doesn't prove anything, since Akuma also called Oro a stupid old fool, but thats not proof either is it...
The Shin Shoryuken that appeared in Alpha 3 wasn't perfected iirc.
It was also stupidly hard to pull off because of the initial elbow thrust.
__________________
"To all visitors from Transylvania looking for the head of Voivode Dracula: Yes, we have it. Yes, he's dead. No, you cannot see it. No, he will not return and invade you again. It has been over thirty years, please stop pestering us."