For those interested in the voice actors involved, here's the breakdown so far (those exclusive to the TV show are italic):
CARLOS ALAZRAQUI: Mesmo, Torts
ERIC BAUZA: Paladum, Mixapod, Miximals
JEFF BENNETT: Camillot, Dribbal, Gurggle, Jinky, Ranger Jinx
STEVE BLUM: Kamzo, King Nixel (second voice)
RODGER BUMPASS: Film Narrator, Flamzer, Gate Keeper, Major Nixel (second voice), Naut
GRIFFIN BURNS: Chilbo, Slusho, Snax
CHRIS COX: Busto, Forx, Gox, Principal
DAVE FENNOY: Boogly, Globert, Kramm, Krog, Medival King, Sergeant
JUSTIN GROLLMAN: Nurp
JESS HARNELL: Burnard, Meltus, Shuff, Vaka, Vulk, Zaptor
PHIL HAYES: Coach, King Nixel (first voice), Kuffs, Rokit
RICHARD HORVITZ: Mixadel
PETER JASON: Major Nixel (third voice), Turg, Wuzzo
TOM KENNY: Berp, Booger, Flain, Seismo, Teslo, Tungster
ANDREW KISHINO: Niksput
PHIL LAMARR: Chomly, Flurr, Tentro
DARAN NORRIS: Amphipod, Snoof, Spugg, Tiketz, Waka
SAM RIEGEL: Vampos
BUMPER ROBINSON: Footi, Glurt, Wizwux
DAVID P. SMITH: Krader, Volectro, Zorch
BRIAN STEPANEK: Magnifo
CREE SUMMER: Jamzy, Teacher
FRED TATASCIORE: Jawg, Major Nixel, Nixels (first voices), Slumbo
MATT TAYLOR: Glomp, Hoogi
BILLY WEST: Balk, Gobba, Lunk
The rampaging Mixeloptors and special vocal effects are provided by Michael Winslow.
A couple of side notes here...
1. No one knows who performed Kraw and Scorpi because their names never appeared in the closing credits. I tend to think it was Fred Tatasciore who performed Kraw because of the way the Series 1 and 2 Mixels were given voices (Kenny, Harnell, and Smith each performed one per tribe in Series 1, and LaMarr and West each performed one per tribe in Series 2, which leaves us with Tatasciore having done Slumbo and Jawg).
2. There are various unnamed kid Mixels seen throughout Every Knight Has its Day. You can definitely make out Jeff Bennett performing the shorter Cragster kid, whom the Mixels Wiki dubbed 'Rocky.' The documentary wasn't kidding about making the show more kid-relatable.
I bet some of the previous voice actors will get to voice some Mixels from Series 8 and 9. What's odd is none of the voice actors will reveal what voices they're performing and we won't find out until the closing credits show up. In some cases, it's easy for us to figure out the voices before the credits - I recognized Cree Summer performing the Teacher and Jamzy and Richard Horvitz performing Mixadel (the latter during the Murpball scene, of course).