if he attacks a scapegoat token do i get to bring out another one
?

"If this card destroys your opponent's monster and sends it to the graveyard as a result of battle..."

since tokens are removed, Geddon's effect doesn't activate, meaning no +1 for you.

The monster that Hydrogeddon destroys as a result of battle must actually land in the Graveyard with Hydrogeddon still face-up on the field in order to Special Summon another one...so NO Tokens will ever be able to activate it since Tokens never go to the Graveyard and it's also why suiciding a Hydrogeddon into another monster with the same ATK will not activate its effect either.