Who could be the main villain in a Batman game story?

Lex Luthor would be a great choice. He could be plotting against both Batman and Supergirl. He might try to use his intellect to create a weapon that can nullify Supergirl's powers and outwit Batman's strategies at the same time.

Another option could be a new villain created specifically for the fanfic. This villain could be someone who has a vendetta against the Wayne family because of something Batman's dad did in the past. He could be a master of disguise and manipulation, making it difficult for Batman and his dad to figure out who he really is.

The Joker could be a main villain. He might see Izuku as a new plaything and try to break his spirit during his training with Batman.

Perhaps an old enemy of Batman who has made a deal with Cadmus. They combine their knowledge and resources. This could be someone like Mr. Freeze, who has found a way to use Cadmus' genetic engineering to make himself even more powerful. His new form and abilities would pose a great challenge for Batman Beyond.

Ink could be a great main villain. He's a character from the Batman Beyond series known for his ability to manipulate ink - like substances. He could target Robin specifically, seeing him as a weak link in the Batman - Robin duo. His powers would pose a unique challenge for Robin to overcome.

Ra's al Ghul could also be a main villain. He might see the child of Batman and Catwoman as a potential weapon or a threat to his plans for Gotham. He could try to either recruit the child to his side or eliminate them, which would put Batman and Catwoman in a difficult position as they fight to protect their family from Ra's al Ghul's devious schemes.

Lex Luthor would be a great choice. He's Superman's long - time nemesis. He could form an alliance with some of Batman's foes like the Joker. Luthor could use his intelligence and resources to create a plan that only Superman and Batman together could stop.

The Reverse - Flash could be a great main villain. He could travel to Gotham to cause chaos and draw out the Flash. His time - manipulation abilities would pose a huge threat not only to the Flash but also to Batman's carefully planned strategies in Gotham. Batman would have to adapt to dealing with a villain who can move at super - speed and mess with time.

The Joker could be a great villain. Imagine if the Joker - like character emerged in the My Hero Academia world. Izuku, with his new Batman - inspired skills, would have to use his wits to outsmart this chaotic and unpredictable foe.

Kingpin would be a very suitable main villain. He has his criminal empire in Hell's Kitchen already, and if he decides to make a move on Gotham, it would bring him into conflict with Batman. His power, wealth, and ruthlessness would make him a formidable foe for the two heroes to face together.