Mario and Luigi Partners in Time Characters
Mario
Mario is the main hero of pretty much all the games with his name in the title, Nintendo's mascot and most of the time round hero to the Mushroom Kingdom (*cough*Donkey Kong Jr*cough*). He is known for saving Princess Peach from Bowser a lot, as well as stopping a variety of villains, such as Grodus, Cackletta, Smithy, Wario, Donkey Kong and soon Princess Shroob (by the end of this game).
Best Statistics- Attack, Speed to an extent
Luigi
Mario's brother and all round coward, Luigi is the second main character in this game. While he has a slight... okay, make that extreme fear of ghosts, he has often overcome his fears and helped his brother stop the various evil doers who threaten the Mushroom Kingdom, as well as saving Mario in a few games.
Best Statistics- Defence, HP to extent
Baby Mario
Mario as a baby (in this game he is slightly older than in Yoshi's Island however), but still as much of a hero as his older self. Managing to try and stop Baby Bowser, and stop Kamek while being aided by Yoshi, he is the main hero of the Past Mushroom Kingdom.
Best Statistics- Speed (very high), Attack
Baby Luigi
Luigi as a baby, he is also a keen hero to stop Baby Bowser from carrying out his evil ideas, and is also pure hearted. He has a few problems though, such as being the baby repeatedly stolen by Kamek, and of crying about the smallest possible thing.
Princess Peach
The person Mario and Luigi nearly always (except in Super Princess Peach) have to save from Bowser, she is the Princess of the Mushroom Kingdom, and is repeatedly kidnapped for reasons relatively unknown. Well, unknown as in the only game when there was a reason behind her abduction was the original Super Mario Bros, where she could turn the population of the Mushroom Kingdom back to normal from the forms of various blocks and items. In this game however, she goes back in time, and pretty much instantly gets captured by Princess Shroob. However, there turns out to be good reason behind the Cobalt Star being shattered!
Bowser
The typical villain and arch enemy of the Mario Brothers in the mainstream Mario games, he is normally the character who tries to steal Princess Peach, and often also some various powerful treasure at the same time. This time however, he's more of a normal boss, and only turns up late in the game, where he is aided by his younger self. However, there is a very strange happening when he eats a certain mushroom near the end of the game...
Professor E Gadd
The inventor of the Poltergust vacuum cleaner, The Flash Liquidising Ultra Dousing Device, the magic paintbrush and the Time Machine from this game, this guy is kind of a semi neutral character in the games. As in, he invents excellent inventions, but doesn't think much before giving them away to various characters, both good and evil. Here, he actually saves you in some areas, such as using a water spraying machine to extinguish an erupting volcano, and to cure the past of all traces of the Shroobs.
Toadsworth (younger and elder)
The chief attendant to Princess Peach, this slightly paranoid Toad is left to take care of Princess Peach, both as a child and as an adult. Very againt anything dangerous however, and seems very reluctant to let Mario and Luigi use the time holes to the past.
Baby Bowser
Bowser as a child, he is still known as evil by those in the past Mushroom Kingdom, and a major annoyance in many parts of the game. First known about when he referred to Yoshi as a 'green donkey', he causes the small annoyance of stealing two Cobalt Star shards, and releasing the Elder Princess Shroob in his mad attempt for treasure right after you've stopped the younger sister!
Kamek
One of Bowser's top Magikoopas, he is most known from the Yoshi's Island games, where he attempts to steal the baby Mario and Luigi, and always abducts Baby Luigi. Also being known to be able to turn small enemies to massive monsters via some powerful magical spells, he is found hiding around Yoshi's Island, and sets various parts of the island on fire.
Princess Shroob
The younger form of Princess Shroob is the main evil force in this adventure game, and is the one responsible for starting a mass invasion of Princess Peach's Castle, kidnapping Toad residents in areas, unleashing Yoob to eat Yoshis, trying to feed Princess Peach to Petey Piranha and various other acts of evil. But as you can find out at the end of the game, she has a twin sister (music from just before the final battle would now play at this point). The Elder form is the twin sister of the Princess Shroob you see at various cut scenes in the main adventure, and is the true final boss.