I was playing New Super Mario Bros 2 when I came upon Toad and repetitively jumped on his mushroom head and heard his character go "ohh" "owe" "ouch" etc. and realized that those noises couldn't be computer generated right? Maybe computer altered, but only a human could make the original noise. So who voices him/her/it?
It looks like the voice actor for Toad has changed over time.
From this Wiki:
Toad's voice was originally portrayed by Tomoko Maruno for the Japanese version of Mario Kart 64 (and later the first three Mario Party titles) and Isaac Marshall for the overseas version. Eventually, Jen Taylor, and then Kelsey Hutchinson, played Toad's voice for many installments. His current voice actor is Samantha Kelly, who also currently voices Princess Peach and Toadette.
So it looks like for the tags you included for your question, Samantha Kelly is your answer!