Hero Type

According to CaptainKodachrome, a character's Hero Type is what kind of hero or villain is according to their abilities, strong suits and weaknesses. For example, because Mario relies on his strength and close quarters combat power, he is the 'Offensive' Hero Type, while Luigi is a 'Support-Magic' character. Every character is designated to at least one Hero Type, though certain characters are a blend of more than one. This has no significance on the story, though it will be important to The Lost Brother Movie.

Hero Types
Every character is at least one of the five hero types: Offensive, Defensive, Speed, Support or Magic.

Though not necessarily a Hero Type, there are characters who are Saviors as well.

Dragon Toadstool
Dragon seems to have a bit of everything in him. He uses fast offensive attacks and high defense maneuvers. He has the ability to use power-ups, just like the other characters and has a bit of technological and sorcery knowledge, as shown many times. Dragon's weakness is Magic.

Mario
Mario is an 'Offensive character, being able to hit where it hurts and keep a consistent flurry of attacks. Mario's weakness is Defense, as he can't take direct hits very well and tends to get launched away fairly easily by bigger opponents (Excluding Bowser).

Luigi
Luigi is a Support-Magic character. He tends to support other characters instead of dive in headfirst and does use magic abilities such as pyrokinesis and invincibility with the help of items. Luigi also tends to be a Savior, taking painful hits for Daisy and helping Mario defeat Donkey Kong.

Rosalina
Rosalina is also a Support-Magic character, using magic to call Lumas to help fight and conjuring Star Bits to heal fighters. She is also a Savior, helping Dragon recover after fighting Kazuya Mishima and using her magic to create a Launch Star to help the others climb to the top of Quicksand Plateau.