One popular plot is the discovery of a common enemy that forces Superman and Homelander to team up, despite their differences. Another is a battle for supremacy in a world where both exist, with different factions taking sides. And then there's the plot where Superman tries to reform Homelander, seeing the potential for good in him.
Well, it depends on how the fanfiction is written. If it's a more 'grounded' version where Homelander's public image and mind - games play a big role, he could potentially gain an upper hand. But generally, Superman has more raw power. He can move planets, and his speed is almost limitless. Homelander is strong and has flight and heat vision too, but Superman just seems to be on a whole other level in terms of pure power.
The main characters are obviously the Powerpuff Girls, which consist of Blossom, Bubbles, and Buttercup. They are super - powered little girls created by Professor Utonium.
Another interesting plot could be a competition between the Powerpuff Girls and the Rowdyruff Boys that isn't about fighting. Maybe it's a contest to see who can do the most good deeds in a day. This would flip the usual dynamic on its head and force both groups to use their powers in creative and positive ways. It could also lead to some humorous situations as they try to outdo each other.