This duel never made it into the original anime (It was in season 0 but heavily altered) but solomon's blue eyes refusing to attack kaiba because he stole it was one of the most goated things ever.
I know if you asked almost anybody, they would say joey deserves to have red-eyes support over atticus cause hes from dm but I would love for atticus to get a wave of red-eyes support. He was the original person to use an entire red-eyes archetype with cards like darkness dragon, wyvern and darkness metal dragon. I know it's not gonna happen cause every red-eyes wave of support has gone to joey, but it would be so cool if atticus got a wave of red-eyes support some day.
I know this is incredibly unpopular of an opinion and a super hot blazing take but destiny hero was cooler back when it was just made of main deck monsters in gx. It gave them a unique identity but when konami made destiny hero a fusion archetype in arc v, they became just another hero fusion archetype and became lame.
Just like many others, I myself hate how joey's new boss monster is designed. It is a very good card going second but is made to be practically impossible going first within the dark time wizard archetype. This card requires the original red-eyes black dragon and the dark time wizard archetype has no way to search it right now. What makes it even worse is that even if you could search it, this archetype also has no fusion spell or main deck monster to help you fusion summon this card. However there is a good reason for this.
Joey's new beyond the brave retrain deck is based on his battle city deck unlike yugi's chaos deck which was based on his duelist kingdom deck. This is why joey's red-eyes is "missing" in action and why you cannot summon it going first. It's because joey lost red-eyes during battle city and didn't get it back until after the tournament was over. This is why joey essentially doesn't have red-eyes at the start of the duel.
As I mentioned earlier in this post, this absolutely sucks in card design if you are a joey/red-eyes fan. It leaves the deck with a lot of issues with the biggest one being the dark time wizard archetype has no boss monster going first. However, in terms of lore konami absolutely nailed it and I applaud them for it. I know people will hate me saying that and I even hate this design, but on a lore scale they did 11/10 with this card's design.
I can't believe how hard they fumbled bastion in gx. The dude was such a cool character at the beginning. The idea that he has several different elemental decks and how builds a new one for each opponent was such a sick concept for his character. His magnet warrior and bonding decks were awesome. He was such a good rival to jaden at the start too. It's a shame that they completely abandoned him, quite literally in the different dimension world too, and that's how bastion ended his story in gx. Quite the tragedy and very disappointing as well.
In the recent gx 20th anniversary duel academia reunion we got a lot of information regarding gx and information we've never known before. One piece of huge information that we find out was that aster originally wasn't going to be using destiny hero but instead he was going to be an elemental hero user just like jaden. They would use the exact same main deck monsters but instead their fusion monsters would be different. So instead of flame wingman aster gets phoenix enforcer. It would have been cool to see his alternative fusion monsters to call like thunder giant, tempest and all of jaden's other monsters.
One of my favorite things about yugioh gx is when you find out kaiba was the person who created duel academy and was in charge of being the owner of the school. Kaiba is very clearly a petty person and I love how much it shows in Gx. It's hilarious how slifer red is the lowest dorm and obelisk is the highest one solely due to his beef with yugi. Yugi uses slifer vs kaiba who uses obelisk in the original series and beats him in battle city semi finals. While slifer isn't the card that yugi uses to beat kaiba, it plays an important role in helping him win that duel. I just love how kaiba is still bitter about that loss so he made his egyptian god, obelisk the highest ranking and yugi's god card, slifer the lowest one.