About Kaito and Edo
Looking back at their background, I kind of get why the ARC-V version trusted each other at a real speed.
Remember when Kaito said to Mizael that he was the real Galaxy-Eyes tamer because Kaito himself just used Galaxy-Eyes to save his family? Edo, with his heroes, was exactly the same. For him, seeing Juudai using Heroes deck because of his adoration in heroes was irritating, because for Edo, he needed the heroes for finding justice of his father's that, he needed the heroes to save him, he used them because his father was the one brought them to him, it was not a pure adoration like Juudai—at least, it was not in the time he was trying to find the culprit of the murder. They were using their respective deck for their own motives, but the deck was also the reason they stood up with pride onwards. What is more important, they both really understood this side of themselves.
It was not like they were alike to each other in personality, but they certainly had a similar point in their way of seeing and understanding things. Even though the background story and their personalities changed later in ARC-V, their roots were not changed. ARC-V was only bringing the different versions of themselves in a different story and background setting. I just really love how the staff might have realised this and made them into an unthinkable duo in ARC-V.