These guys have done enough voice work to qualify as proper voice actors.

I read somewhere that HeiHei was originally written as intelligent and capable of speaking, and Tudyk was meant to voice that version. When they changed the character to "the stupidest animal sidekick in Disney history" (to quote one of the directors), they decided to use Tudyk anyway (and also gave him another role:…

Apparently he was supposed to voice Ratcliffe in Pocahontas, but the directors feared it would sound too much like a Gaston rehash…

Yeah, the series you're referring to is basically the Italian division of Disney doing their version of Marvel, with aliens, time travel and whatnot. It's more serious than the "classic" Donald superhero comics, which are published in the weekly Mickey Mouse magazine (in Italy), and features very few classic Disney…

That may be true, but they still record the show as a group (sans Shearer). Generally speaking, voice actors use home studios for solo gigs (narrations and such).

Not really. Some details make more sense if you've seen all the movies, but overall the MCU films are pretty self-contained, with the necessary backstory conveyed through dialogue.

Same reason they couldn't use Batman, Wonder Woman, Green Lantern and Flash (no, Impulse doesn't count): the film division said "No, we're using him."

They haven't shown Sudeikis because :