>

Pokemon hasn't really covered alternate universes besides having a few throwaway lines in a remake referencing the original version of the game. The rest has been heavy fan speculation (besides Ultra Space, but I'm not even sure if that counts).
Doctor Who has had two TV stories since the revival in 2005 that were related to parallel universes, and even those stories were connected.
Shrek was time travel, not multiverse.
There exists a universe where the multiverse is interesting >

Jjba >

Multiverses destroy stakes and consequences. Almost as ridiculous to use as time travel. >

Time travel / multiverse done right is an effective combination 
steins gate for example >

In another genre, Everything Everywhere All At Once is pretty freaking great >

anime isnt a genre.. its a medium >

Steins gate is a scifi-drama, everything everywhere is a comedy... >

It's a science fiction comedy. >

Nobody exists on purpose. Nobody belongs anywhere. Everybody's gonna die. Come watch TV. >

Where Marvel uses the multiverse to just expand the cow to milk, >

wait, besides EEAAO and dr Strange, what else is using multiverse as plot point in movies? >

Almost every superhero has gone into it at some point (superman, flash, Spider-Man, venom, etc).  
Star Trek, Shrek, Dr. Who, Phineas and Ferb, Twilight Zone, Futurama, Simpsons, Pokemon, Buffy, Community, even My Little Pony has done it. 
In terms of movies you got Back to the Future, Another Earth, Butterfly Effect, About Time, Mr. Nobody.