I've decided to replay the Paper Mario series for both nostalgia value, and to accurately type the characters as best I can. Note though, I'm currently only typing the characters from the first game, not the second two (I'll type those characters when I get around to playing those games).
Mario - virtually no personality within the game, and is probably untypable for the most part, aside from maybe being an xSFx.
Bowser - ENTJ 8w7 sx/sp - at first I wasn't sure about Bowser, but seeing as how he wants conqur Mushroom Kingdom, kill Mario, and claim Peach as his bride, not to mention his general scheming, Te+Ni with some Se seemed to make sense. Se dom could be possible.
Peach - ENFJ 6w7 or 9w1 or 2w1 so/sx - seems like an Fe dom to me, but to be honest I'm not certain on the typing since it's based more or less on my gut feeling.
Twink - ISFP 2w1 sx/so - adorable little guy who wants to help his freinds; Fi dom is clear, no visible Ne so Se by default, could be 6w7 as well.
Goombario - ESTP 7w6 sx/sp ISFp - at first I thought Si dom because he was a walking encyclopedia of information, but beyond that seemed to be an excitable adventurer who only wanted to go on an adventure with his herp Mario, which seems more Se, that and his constant observations of the current physical environment. Clear Si dom under socionics.
Kooper - ESFP 7w6 sx/sp - basically a bit of a clone to Goombario, could be ESTP, but there isn't much information to work off from him.
Kolorado - ENTP 7w8 sx/so - explorer with a knack for risking his own damn life in the process.
Spike (Lakitu ally) - ISTP? 4w3 sx/so - wannabe poser who changes his name cause he wants to be cool, seems like 4w3 to me, not sure at all on his JCF type.
*Note: the rest of the ally characters don't really have much in the way of character development, thus their typing are based solely off supificial appareance. those that weren't typed didn't really have much in the way of a personality.
Bow - ESFP 4w3 so/sx
Parakarry - ISTJ 5w6 so/sp
Sushie - ESFJ 2w1 so/sx
JR Troopa - ESTP 8w7 sx/sp - stubborn bully who wants to beat up Mario, Se dom and 8 seem obvious here.
Kammy Koopa - ISTJ 6w5 sx/so
All the magician sorcerer characters - INFJ 5w4 sp/so