In a Danny Phantom - Avengers Endgame fanfiction, Danny might have to adjust to the very different world of the Avengers. The Avengers, on the other hand, would be both amazed and a bit skeptical of his powers at first. But once they see what he can do, they would start to incorporate him into their battle plans. For example, Danny could use his ecto - energy blasts in combination with Iron Man's repulsor beams for a more powerful attack.
It could be a wild crossover. Danny Phantom could use his ghost powers to help the Avengers in the final battle of Endgame. Maybe he could phase through enemies and surprise them. His intangibility and invisibility would be great assets.
Well, this fanfiction could start with Danny being somehow transported to the Marvel universe right before the events of Endgame. He would be confused at first but quickly realize the gravity of the situation. The Avengers would initially mistake him for an enemy due to his otherworldly appearance. However, as Danny tries to communicate and shows his willingness to help, they would gradually accept him. Danny's ability to fly and his super strength as a half - ghost would make him a valuable addition to the team, and together they could face Thanos in a more epic and unique way than in the original Endgame.