Pokemon- I would not have Pokemon be the 'default' wildlife. In the earliest lore there were ordinary animals alongside Pokemon, Pokemon had arrived to Earth thousands of years ago, they were not of Earth. That made far more sense, that would explain why Pokemon were really special, and why people sought them out. Going with this, I'd have gone further and made them rare and very slow to breed. If Pokemon are very rare and special and people have to actually search them out, then it makes sense for people to get excited over them and form clubs. Finding one (and successfully being able to tame it) becomes a cause for celebration and bragging rights. Making them rare also means people will treat them like trophies and weapons and not like living things, which seamlessly leads into plots like MewTwo and other legendaries.
My other fix for Pokemon would be to have another cartoon with a much more darker take and more realistic art style, like that dark cartoon 'trailer' that is on YouTube. Sometimes a series need to grow up or they will forever be stuck in the kiddy age ghetto.
Batman vs Dracula- This one is very nearly perfect, but my biggest gripe is that it does what every comic book movie toon does: It takes a good idea and at the end resets it back to the bland boring status quo without ever developing it further.
My change would be to the Vampirism itself and some of the plot- it's not a disease or curable, when Dracula turns you it's because he drained you and made you drink his blood. You die and come back a walking blood-sucking corpse after that. That would make what Joker becomes more horrific, give Bats a huge quandary about whether or not to keep Joker 'alive' and contained in Arkham Asylum or if he should destroy him, and in the process try to avoid getting drained/turned himself by either Dracula or any other vampire. I would also not have too many vampires created besides Joker and two or three others (maybe just Poison Ivy and Two-face) but the other baddies Batman fights would just be ghouled mooks, living mooks and living supervillains like the Penguin and such. Penguin and the rest of the living baddies would be utterly terrified of the Joker and of getting on his bad side, if dealing with him before was nerve-wracking then dealing with him as a vampire would be pure nightmare fuel. This movie would also not be a one off, it would be the introduction into a mini-series, because seeing the Bat fighting Drac and Vampire Joker is just plain awesome.
Samurai Jack- I would have scrapped everything past the first 3 episodes of the 5th Season and just had him search out and kill all of the Daughters and finish off Aku. He never acts shocked or horrified that he kills anything, when he's done he says goodbye to all his friends, and goes through the time portal that has that cool Guardian, kills off Aku in the past, marries Grasshopper Girl and makes a bunch of babies.
