We're going to keep this post as far away from spoilers as possible. Be warned that if you click over to the source link, major elements of Detective Pikachu's third act will be spoiled.
The third act in Detective Pikachu takes some wild twists and turns, and a lot of that required some bigtime visual effects. In an interview with i09, VFX supervisor Pete Dionne talked about walking the tightrope of having things look realistic instead of like a cartoon.
“Where we ended up was very calculated. Rob Letterman, our director—the first thing he said was, ‘This can’t look like magic, and it can’t look like cartoon-y glows, this needs to look like real, physical events. Like, I want to see electricity and plasma. Things I understand, physically, what they are, but at the same time—I want these to be moments for the audience and fans to not roll their eyes, but get excited and see the respect we’re paying to the Pokémon world.’”
The full feature talks about specific effects, how they were created, and designs of other Pokemon. Again, it's all very much spoiler territory. If you're okay with that, click here to check it out.