I wan't to express, that I disliked Rick and Morty season 3

[Homeless Nutter]

About Mr. Poopybutthole, his name has never bugged me, it's alright if you don't like it. Actually, I thought his name was funny at first, but you know that every joke stops being funny after you hear it more times. It's not a bad thing to give characters a funny name, as long as it's not offensive and you do good jokes with it.

I don't have a problem with the character, or the joke name. The whole charm of the joke is that it's dumb, infantile and random, yet it's played uncharacteristically straight.

My point is - "lazy" writing is one of the defining elements of "Rick and Morty". It's everywhere, including in Roiland's dialogue, which intentionally sounds not only unrehearsed, but often unscripted, as if the voice-over artist got a bit drunk and started making stuff up on the spot (which is probably what happens). It's in the random, meaningless catch-phrases, like "Lick-lick-lick my balls!", or "Get shwifty". It's in the Intergalactic Cable episodes, which are mostly just collections of throwaway ideas, that nobody can be bothered to develop, or work into regular episodes. It's in very prominent references to pop-culture, to the point of entire episodes based around popular movies, often mediocre ones, like "The Purge". The entire show started as a cheap parody of "Back To The Future"(Rick and Morty = Doc and Marty).

If you allow all that - you can't really blame the writers for not coming up with more convincing way for Evil Morty to gain power, or what-not. It might be dumb and unrealistic, but so is the entire show - and that's where lies a lot of its charm.
You shouldn't over-think it. The show's creators clearly don't.

To the show's credit, it doesn't overuse the name, but there are other problems with this character. They made him a wife that follows the Minnie mouse principle, that means looking like the male character in drag. Seriously, they didn't even give her a different hat, and that is a masculine hat. I have nothing against females wearing men's clothing, I myself want to do it sometimes, but that doesn't excuse laziness, the hat could've been different and still masculine. They also made the baby look exactly like the father. You can't get away with this, unless you're using it for a good joke or you give an in universe explanation. They also tried to make a joke about Mr. Poopybutthole living a normal life, which isn't funny. It could've been funny if we saw other people's reactions to his name and/or appearance.

You see - you're over-thinking it. As I said, the whole point of Mr Poopybutthole is the fact that it's a ridiculous and lazy idea, which nobody within the show's Universe ever acknowledges. If the creators made him and his family fully fleshed-out and well designed characters - it would work against the joke.

Or maybe - just maybe - Mr Poopybutthole is... god. He showed up out of nowhere, yet everyone treats him like a life-long old friend. He's ridiculous and out of place, but nobody makes fun of his name or his looks - not even cynical Rick. He knows he's in a cartoon and has the ability to follow the story, without actively taking part, as well as to address the viewers directly. His family look like him because they're one person - a Trinity, if you like...