in the other media
I heard some talk from the directors of Detective Pikachu discussing a Smash Bros movie. While I'd like to see that, there is often an incorrect analogy made between the video game series and the MCU movie franchise. In fact, when we acknowledge this fact, and THEN ask what the structure would look like in the alternate media, we can some worth while answers.
A quick summery of each Structure. Smash Bros is a game with popular characters (usually, but not always main protagonists and antagonists) from various, independent video game series. The Marvel Cinematic Universe is an ongoing story franchise with different stories told within the same shared world, with some stories involving an especially large gathering of popular characters for a single story. At face value, these may seem more similar than different, but I want to give some examples of what these might look like in the opposite media to clarify the discrepancies.
A Smash Bros Style Movie
This is a crossover film with popular movie characters meeting each other in a story. Some characters with similar goals may team up, or they may not at all. The story will tell multiple simultaneous stories that may be only loosely connected like Pulp Fiction. At the end of the film each of the characters will reach their own narrative conclusions, and they will go their own way. Usually none will die unless that character will not be in a sequel in their own franchise again, and the canonicity of this film may be left ambiguous in future installments of the individual film franchises.
The more likely a character is to continue in their own franchise, the less likely they are going to experience things that cause them to question their beliefs or change. There may be characters that are familiar with magic and those that are not, and if not may not encounter it or have rational reasons to doubt it. Or their experience in the film may just be not canon in their own series.
An MCU Style Video Game Series
This is a collection of video games with very different gameplay. Occasionally, there is a crossover installment that incorporates the gameplay from the past entries. The individual games may have subtle or dramatic influences on the other entries, and the crossover will likely have dramatic influences on all.