Goku as God of Destruction might have new abilities related to the concept of destruction itself. He could perhaps manipulate the very fabric of reality to cause destruction in ways that normal Saiyan powers wouldn't allow. His ki attacks might also take on a different, more menacing form that reflects his new role.
His powers would likely be more about destruction in a controlled and purposeful way. Instead of just fighting to win battles, he'd be able to use his energy to completely obliterate things at a much larger scale. For example, he could destroy entire star systems with a single blast if he needed to.
His power would be more about judgment. He wouldn't just fight strong opponents for the sake of it. He'd have to decide who or what is a threat to the balance of the universe and use his power accordingly. So, his power would be less about self - improvement in combat and more about maintaining the order of the universe through destruction, which is a very different mindset from his previous power - seeking self.
Another great plot could involve Goku facing off against other Gods of Destruction who don't believe he's worthy of the title. This would lead to epic battles where he has to prove himself not just with his power but also his newfound sense of divine responsibility.
The manga might have more detailed storylines and character developments that aren't fully shown in the anime.
The plot might involve the new God of Destruction facing a powerful threat that even the other Gods of Destruction can't handle. He has to gather the strength of all the Saiyans and other allies in the Dragon Ball universe. This could lead to new power - ups for characters like Goku and Vegeta as they train to fight alongside the new God.
Their powers could combine in a fusion. Just like how Goku has fused with Vegeta in the past, he could potentially fuse with Caulifla. This would create a new and extremely powerful warrior. Their combined Saiyan powers along with their unique fighting styles would make for an unbeatable force.
In Dragon Ball fanfic, Goku SSJ often has super strength, like being able to lift extremely heavy objects with ease. He can also move at incredible speeds, making it hard for enemies to even see him coming. His energy blasts are much more powerful than in his normal form, capable of destroying large structures or powerful foes in one shot.
Vegeta would be a great addition. His rivalry with Goku and his pride as a Saiyan would add an interesting dynamic. He might be initially jealous that Goku is getting to fight and train with the God of Destruction. But then he would also want to prove himself and join in the action. Whis could also be included. His knowledge and calm demeanor could help in situations where the power of Goku and the God of Destruction gets out of hand.
In the original Dragon Ball, Goku is mainly a heroic figure facing external threats. In the 'goku is abused fanfiction', the threat is internal, coming from abuse. The original focuses on battles and power - ups, while the fanfiction is more about Goku's internal struggle.
Vegeta could be a great rival. He might see Goku's new position as God of Destruction as another thing Goku has achieved that he hasn't. This could fuel their competitive nature even more.
It could be a Saiyan. Since Saiyans are known for their strength and love for battle. A Saiyan could be chosen to become the new God of Destruction, like Goku or Vegeta's descendant who has a unique power that makes them suitable for the role.
Perhaps a fanfiction where Vados senses a new threat approaching the universe. She enlists Goku to help her find a way to stop it. Along the way, they encounter strange new races and powers. Goku's simple but powerful approach to fighting combined with Vados' wisdom would make for an interesting dynamic as they search for a solution to this impending doom.