In MK64, D.K.'s sound effects were done by Charles Martinet.
Which means that he was the voice for half of the characters in the International version (Mario, Luigi, Wario, & D.K.)
In the Japanese version (as well as the N64 Mario Party games), however, he only did the voices for one fourth of the characters (Mario & D.K.), as Luigi & Wario were done by two completely different people.
Additionally, since D.K. actually had a proper voice actor in MK64, only one fourth of the characters had "voices" produced by some sort of non-human sound thing (Yoshi & Bowser)
Wario's "D'oh, I missed!" line from MK64 JP, MP, MP2, & MP3 could also actually be him speaking something in German.
In Super Mario Advance, one of Toad's voice clips could possibly actually belong to Peach.
Said voice clip is one of the yelps he utters when taking damage. This particular one isn't as "scratchy" as every single other voice clip done for Toad in SMA.
Also, oddly enough, the version of Rosalina's voice (the one from SMG, SMG2, & MKWii) that sounds the least like Peach's was done by the same voice actress as Peach's.
And the voice for her that's been in SM3DW and MK8 (the one that sounds even more like Peach's) is done by a completely different person.
Another strange thing is that Princess Peach's voice actor is not listed at all in the SM3DW credits.
If one counts the cartoons, & Hotel Mario, Waluigi is the only regularly appearing Mario character to have never gotten a different voice actor. He's had the same one since Mario Tennis (N64)
If one does not count the non-game, & non-CD-i material, both Waluigi and Mario have had their respective voice actors since their debut (and in Mario's case, since he was first given a voice)
And it just so happens to be that both characters have the same voice actor!
The voice actors for Toad and King Koopa in The Super Mario Bros. Super Show were the only voice actors to have worked on all 3 Super Mario cartoons. For Super Mario World, Toad's voice actor did multiple other characters instead, like Oogtar, Wizenheimer, the Monty Moles, and the Koopa Football Players. King Koopa's voice actor however was the only voice actor to have played the same character for all 3 cartoons.
Additionally, Yoshi's voice actor in the Super Mario World cartoon also was Diddy Kong in the Donkey Kong Country cartoon.