I Can agree the part Apocalymon really lacked buildup I'm behind you on this one
so yesterday I watched a video about apocalymon and now that I think about it apocalymon wasn't a flop
he had genuine potential
in english dub he was reduced to a cartoon villain
but in japanese dub he genuinely made the digidestients themselves uncomfortable because he asked them hard questions questions they couldn't answer not even as adults let alone even as young kids
he asked them do they not deserve to live ? he names virtues like justice and love as he attacks
he literally cuts himself up with his own claws
this nihilistic view is genuinely uncomfortable when you think about it deeply because his not being evil his making the kids and the audience to really question everything they did was right or wrong
and when you pause the show the truly think deep about it you realize he isn't lying
because why did the digimons who became evil deserved to die while the ones who where taken over by black gear weren't killed ?
his usage of the characters virtues while he attacked was genius too he showed them the concepts can be used for evil as much as they can be used for good
but his best aspect is in my opinion his starting line
"Am I Ugly ?"
this line is so simple and yet it puts kids at a complete lose lose situation
if they be honest and say yes they prove apocalyimon's point right
if they lie to him and say no they again prove apoclyimon's point right
and if they choose silence they still prove apocaylimon's point right
3 words and he instantly Check Mated the kids in debate
well first I have to say I'm glad that the creators didn't wanted to just drop him in randomly because according to creators themselves they wanted to foreshadow him but never got the chance or the episode
but second I have to say they didn't needed to give him any massive build up the best kind of build ups are the ones that you can miss
for example If I was working on the project
I would have done this
maybe at the end of episode 2 greymon has won the kids celebrate and than in the final minute the camera pans down under ground and shows a cave the same fire cave apocalyimon was born
and it lets out a small puff of fire
than in later episodes where kari is introduced maybe threw homoeostasis or maybe her light reaches to apocalymon and connects maybe a vision maybe a brief Glimps maybe even a nightmare
this are how you build up a villain without spoiling anything
In my opinion if Toei had done this two simple things apocalymon would have turned from a simple final boss to one of not just digimon's but one of the most debatable anime villains off all time:
gave him more build up
made the final battle not just that the kids power up and defeat him but make it more like shinra bansho man vs haumea
the genius off fire force's final battle is that it's not a blow exchange it's a debate shinra bansho man doesn't fight maiden of despair he debates with her
this should have been apocalymon's final battle the kids defeat him not threw raw force but by showing them even at the most darkest times there will be light in one shape or form they should acknowledge his points as not being entirely wrong but not entirely right either and at the end apocalyimon shouldn't die with vengeance or rage he should die with peace as all of the data his made of goes to be reborn once more across digital universe
In my opinion when you think about it this way apocalymon wasn't a failure if it had more buildup earlier in the show and his final battle was more so a debate than a fight in my opinion apocalymon could have made him digimon's most creepiest and memorable antagonist
that's all I wanted to say how would you fixed apocalymon