This is probably a stupid thing to make a topic about (Mario games are known for pretty much everything
but the voice acting, and I can't think of any Mario games I've played outside of Super Mario Sunshine that even have fully spoken dialogue.), and I'm not good at explaining subtle differences, but whatever.
I've noticed that the voices of Mario characters are rather inconsistent. Mario, Luigi, and Wario's voices are more or less consistent, and just feature subtle differences between games. Other characters, like Peach or Toad, can have radically variable voices between games (although Toad's voice has been pretty much the same in every game since Luigi's Mansion).
Mario sounds a bit crackly in certain voice samples from Super Mario 64. ("Yah!" "Wah!" in particular) and his voice is generally a bit lower than in later games. I could perhaps blame both of those on the compression of his voice samples to fit in the cart.
In Mario Kart 64, Mario's voice is awesome, all elegent sounding and stuff. Hard to explain what I mean, but this is probably my favorite incarnation of Mario's voice. In the original Smash Bros, Mario's voice sounds mostly like it does in 64.
In Melee, his voice sounded somewhere between his voice in the previously mentioned N64 games and his voice in Sunshine. In Sunshine (which is my second favorite incarnation of Mario's voice, by the way), he sounded a bit different than in all of those, and probably sounds more like he does today. Most of the differences I hear in these voices are very subtle and hard to describe, and I'm sorry about that. They're there, though. In the Galaxy games, Mario's voice sounds a bit more...I dunno, like it's cracking I guess? You can hear it in the game when jumping and stuff, but it's also noticeable even in the little "Disc Channel" selection thing. It's a lot easier to hear the differences between his Galaxy voice and his pre-Galaxy voice. Maybe Charles Martinet's voice is fatiguing from doing that super high-pitched voice?
In earlier games (Like the first two Smash Bros games and I THINK the N64 Mario Party games, but I've never played any Mario Party before 4), Luigi essentially just sounded like a higher pitched version of Mario's voice. It should be noted, though, that this is inconsistent, because Luigi was given a completely different voice from that in the localization of Mario Kart 64 that's a lot closer to his current voice.
Luigi's voice was at its best in the American (More than likely European too) version of Mario Kart 64.
Luigi's voice got more "crackly" (I guess that'd be the word to use?) in Luigi's Mansion. It still sounds like his MK64 voice, more or less. Nowadays, Luigi's voice sounds "wimpier", which I guess is an attempt to play up his "constantly scared" character trait he earned from Luigi's Mansion. It's really noticeable in Brawl.
I'm not going into detail with a bunch of links and stuff for everyone else, sorry. But anyways, it seems like Wario sounds a bit less "sinister" (that's a bad way of putting it, but oh well) than he was
in earlier games. Other characters have underwent much less subtle changes. Princess Peach's voice went from
this, to
this, to her current voice, thanks to cast changes (from Leslie Swan, to Jen Taylor, to Sam Kelly) resulting in completely different voices. And I gotta say...I like Jen Taylor's Peach voice the best. Toad started out
simply sounding like a shouting child,
but now he has this weird, high pitched raspy kinda thing going on. Bowser usually used voice samples of roars up until Sunshine, where he got a voice. Bowser's voice in Sunshine is very widely criticized, but I personally really liked it. It was deep and "evil" sounding enough to sound believable as Bowser, but he also sounded really goofy at the same time, and I liked that. In that cutscene where Mario confronts him, he almost sounds like Brian Doyle-Murray. Everyone else hates it though. His voice in Galaxy and onward is a deeper and growl-y, you could say. Those are all the characters I can think of at the moment.
