Oh boy, it's almost as if this entire thread was designed and tailor made for me.
Well anyway here's a list of some of the character voices from every region I really like a lot (all from the English dub btw and mostly for the more major characters aside from a certain few I'll include because otherwise we'll be here forever, and you'd be bored senseless):
Kanto: Misty (Rachael Lillis's take btw, Michele Knotz is alright but rather spotty with the S&M reprisals),
Brock,
Jessie (I do like both Rachael and Michele),
James (Ted Lewis and Eric Stuart, just not the later stuff from Hoenn though),
Meowth (Maddie Blaustein),
Professor Oak (Stuart Zagnit),
Giovanni (Ted Lewis, I know it was only for one or two episodes but Craig Blair's is just.... no),
Sabrina,
Koga,
the Pokemon League announcer (just so iconic and I kinda wish we saw Ted get another shot again)
Johto: Professor Elm,
Bugsy,
Morty,
Jasmine,
Chuck,
Lance (more his recent Journeys appearance than the older ones)
Hoenn: May (Veronica Taylor),
Max (Yes, Max is annoying but I'm amazed at how well Amy Birnbaum did with making him not sound too nerdy, which TAJ was guilty of with Kayzie Rogers's performance),
Drew (Oliver Wyman),
Harley (I don't know why but Bill Timoney is just really fun to listen to although Andrew Rannellls is also great as well),
Professor Birch,
Steven Stone,
Roxanne,
Drake,
Juan,
Tyson, (It's Marc Diraison... as a rival for Ash. What else can I say?
(Well other than the Hoenn league kinda sucked but this isn't a place to rant.)
Noland, (Really the only Frontier Brain alongside Tucker that sounded very good)
Tucker
Sinnoh: Dawn (How could I not have Dawn on this list? Emily Bauer started rather rough with the TAJ episodes but pass that era and into the DuArt stuff, she really makes the role her own.)
Paul, (The best kind of asshole rival and Julian Rebolledo nailed it perfectly)
Barry, (Shame Jamie McGonnigal doesn't do much voice acting anymore because I miss him with how fun he was as Barry)
Cynthia, (Another banger of a role from Emily Bauer, let's hope she's still got it once the dub reaches her return)
Reggie,
Looker,
Saturn, (My favourite voice from the Galactic team)
Charon, (Second best voice of the Galactic team)
Hunter J,
Marble, (Yes, it's a COTD but it was my introduction to Cassandra Lee Morris as well so props for that)
Maylene, (This region has some real banging VA's for the gym leaders and it truly kicks off with Rachael Lillis as Maylene)
Crasher Wake, (J. David Brimmer really has that unique voice that I kinda miss hearing on the show, I like him a lot)
Angie,
Byron, (Easily my favourite of the gym leader voices with how Dan Green just went all out nuts with his voice, it really does sound like he had a great time in the recording booth)
Riley, (It's Marc Diraison. What else can I say?)
Candice,
Lyra,
Flint,
Volkner, (I wonder how the new Journeys VA will fare considering it's most likely Eli James won't be returning)
Tobias (The controversial Action Replay cheat using man himself, voiced none other than J. Michael Tatum)
Unova: Cilan,
Professor Juniper,
Don George,
N, (I'd still say that Nicholas DiMichele is the best voice for N as of now and the others still haven't come anywhere close to him yet, well maybe Daman Mills if he had better voice direction)
Stephan,
Pierce, (It's still a god damn shame this guy disappeared)
Dr. Zager,
Chili,
Colress,
Burgh, (Billy Bob Thompson's first major role and he certainly left a good impression)
Ingo,
Emmett,
Drayden,
Roxie,
Barret,
Kalos: Serena,
Clemont,
Bonnie,
Professor Sycamore, (Jake Paque's one of my favourite NY VA's so of course Sycamore had to make the list)
Mairin,
Squishy,
Meyer,
Diantha,
Gurkinn,
Shauna,
Tierno,
Trevor,
Sanpei,
Malva,
Grant,
Ramos,
Olympia,
Wulfric, (My favourite voice of the Kalos gym leaders)
Lysandre, (Still the best villain performance in the anime hands down, Tyler Bunch nailed it to perfection)
Astrid,
Remo
Alola: Kiawe, (My favourite of the Alola companions voice wise)
Sophocles,
Professor Kukui,
Professor Burnet,
Samson Oak,
Gladion,
Hobbes,
Acerola,
Viren,
Molayne,
Tupp,
Zipp,
Plumeria,
Wicke,
Faba,
Hala,
Nanu,
Laki,
Ikari,
Ulu
Journeys: Goh, (I don't care for Goh himself but Zeno's a lot of fun in the role)
Chloe,
Professor Cerise,
Leon,
Raihan,
Chairman Rose,
Oleana,
Wikstrom
And that's my main list.
Well, a Pokémon voice I do like is Pikachu but I'm not going too deep into that.
