Pretty straightforward. What classes do you think the characters from DBZ would be.

For example: Trunks = Swordsman, obvz.

Some characters can cross-race-class though, just for fun..I guess.

Goku = fighter
Vegeta = fighter
Piccolo = dark warrior
Krillin = turtle hermit (mostly because of his ki based attacks)
Yamcha = Some sort of spiritualist because of spirit ball
Tien = Crane hermit
Chiatzou = Crane hermit
all i got so far

Nail, Shadow Knight IMO
Kid Buu: karma Maijin OR Ultimate Maijin, ( hard to tell cuz the dude doesnt need weapons, BUT he has used ki based atks and phy so idk)
Gohan = Fighter OR Swordsman (not sure cuz the dude has had a staff at 1 point in the series and a sword at another)
Maijin Buu= Plasma Maijin Imo

Someone needs a taste of the Wolf fang fist, methinks.

i think that goku have of all classes a bit
from martial and spiritualist

That's cuz he haxorz

goku mix balanced
vegeta mix leaning more to martial artist
piccolo+nail+kami a mix cus they are fused
yamcha martial artist
tien spiritualist
krillin spiritualist
gohan mix imo leaning a bit more to the spiritualist
goten same but leaning towards martial artist
trunks swordsman

Goku-fighter
Vegeta-fighter
Yamcha-swordmaster(he had a sword at the beginning of the dragonball series)
Tien-Crane Hermit
Chiatzou-Crane hermit
Krillin-Turtle Hermit(since he did take over the turtle class teachings)
Piccolo-Dark Warrior(more bcuz of hellzone grenade)
Nail-Shadow Knight(guess cuz ik hes not like piccolo but he is a physical)
Majin buu-Ultimate Majin(buu did a lot of combo hits like the ultimate majin)
Cell-Poko Priest( he spat the cell juniors which means he asexually reproduce like the namekians)
Evil King Piccolo(piccolo's dad)-poko priest(he spat out all those monsters including present piccolo)
Gohan-Turtle Hermit(his attacks are mostly ki based but im only going off of DBZ games on this 1)

I can think of more for other characters but ill only do those upon request cuz im not sure wat characters you want this is just like a basic guide

^Cell=/=Poko Preist. Because he's an android. However he has the DNA of many of the Z-Fighters which would make him almost all of the Classes with the exception of all Majin and Dragon Clan

You really can't fit characters into classes because for the most part, they don't use weapons. Especially for the MAs and characters like Gohan who grew up learning Piccolo's techniques, but then mixing his father's moves in.

Goten/Trunks=Swordsmaster (They made the Swordsmaster School.)
Krillin/Roshi=Turtle Hermit (Turtle School/New Turtle School.)
Tien/Chiatzu=Crane Hermit (Crane School.)
Dende= Dende Clan (Obvious reasons.)
King Piccolo= Poko Preist (He spits those monsters out of his mouth like the Poko Preists.)
Vegeta=Fighter (His move Big Bang Attack is a Fighter move, but he wouldn't use a Pole, because doesn't like poles.)

Goku and Yamcha seem to be in between MA and Spiritualist, because Goku was a Turtle School student, yet he also defines many characteristics for the MA class (Moves in the Spiritualist and Turtle Tree are a part of Goku's arsenal. But Goku is known for some of his physical moves and he once used his Power Pole, making him an MA gone Fighter.) Yamcha would be like Goku in the basis of Spiritualist gone Turtle for the same reasons, but since Yamcha didn't progress much in fighting, he'd simply be an MA, I can't see him being either Swordsman or Fighter.

Gohan is in the middle of an MA and a Namek class Human. He could be a Swordsmaster as he did hold the Z-Sword in the later part of Z. As for being a Namek he did have Masanko and other Namek moves in his arsenal, though he really wouldn't be a Namekian. He's an odd-ball that Gohan is.

Haha
If they put Androids as an race then Cell will be that, in other case no.