Well, you've got the 3 traditional stunty teams : goblin, halfling and Ogre
Plus if you drop the Saurus and skaven you've got two more from the orginal 24 BB teams in : Lizardmen and Underworld. I would add another Kroxigor to the all skink stunty lineup and either another warpstone troll and a warpstone fanatic to the underworld stunty roster. Or keep it one troll and add two warpstone fanatics with 50k bribes. I really like the fluff of mutation access on a fanatic!
So that's 5 stunty teams from the original BB teams.
If your are going to invent some new stunty rosters you need to keep in mind the core values of stunty teams which I think are
Strength never above 2, armour never above 7, stunty skill (d'oh, I know), dodge skill, No access to normal skills without a double roll, and big guys.
First you could have some fluff about necromancers being feed up with killing so many stunties but their reanimated remains not been worth putting in their main undead teams. So they get together and have yearly undead stunty cup.
Undead Halflings or Deadflings (copywrite!)
Deadfling 0-16 MV 4 ST 2 AG 2 AV 6 dodge, stunty, right stuff, regeneration, thick skull. Agility skill access
Deadfling Mummies 0-2 MV 3 ST 5 AG 1 AV 9 Mighty Blow, Regeneration, Throw Team Mate
No treemen cause of the difficulty of reanimating wood, so mummies drafted in and taught to throw fling. I really like the idea of resilient but still squishy zombie flings!
Undead Gobbos
Zombie Gobbo 0-16 MV 5 ST 2 AG 2 AV 7 dodge, stunty, right stuff, regeneration. Agility skill access
Don't know what do about trolls. Undead trolls doesn't seem like a nice or fluffy fit. Take Flesh Golems instead? No TTM for them if so. Or could have some fluff about how secret weapon gobbos seem to die twice as quick as normal goblins and increase the available slots to two for undead versions of the gobbo secret weapons. i.e. You could take up to two Zombie Looneys at MV 5 ST 2 AG 2 AV 7 regen, chainsaw etc, etc. But having up to 8 players who could be sent off in a match maybe too much. Still if they were only going up against other stunty teams you wouldn't expect too many restarts so it wouldn't be that much of a problem.
Undead Ogres is a possibility, but I would limit the Zombie Ogres to 4 as dead Ogres are far rarer than dead snotlings! I would nearly not give the snots regen as there would not be too much left after a tackle to be reassembled.
Would skip undead skinks and underworld gobbos altogether.
Next, since the elves get like umpteen different versions of themselves you would have to do the same for the 'Flings!
First Darkflings. These are halflings who have turned their back on fine cuisine to embrace depravity and fast food! Minotaurs instead of treemen and two stabflings.
Darkfling 0-16 same stats as normal halfling
Stabfling 0-2 MV 5 ST 2 AG 3 AV 6 dodge, stunty, right stuff, stab, shadowing.
Darkfling Mino 0-2 MV 5 ST 5 AG 2 AV 8 Horns, Frenzy, Mighty Blow, Thick Skull, Loner, Always Hungry, Throw Team Mate, Wild Animal.
The Stabflings so have be represented with giant stabby forks instead of knifes
Technoflings. Like how gobbos have loads off secret weapons to hurt players, make a fling team with heaps of steam-punk secret weapons to win games. Only one treeman, but with a clockwork eye, i.e. accurate skill. Next you want about 4 secret weapon guys. Most of these ideas all shameless knicked from pug
Steam driven arms, like grot-oc. I.e. a fling with Doc-Ock style arms. Skills would be secret weapon, multi-block, extra arms (of course), sprint and diving catch.
A blunderbuss guy like Farblast
An armour suited guy, give him AV 9 ST 3 MV 6 secret weapon, but he's not allowed to use the stunty skill when dodging?
And finally a mechofist guy. Just a 'fling with massive metal mechanical fists. You could mod a fling with mighty Zugs fists.

ST 5, secret weapon and mighty blow. Again maybe lose the stunty ability when dodging?
Or a Techfling deathroller?
That's 8-10 teams just using the current BB teams as a base. Not sure about undead Gobbos and Zombie Ogres.
Starting brand new teams is always harder to get the balance/fluff right but how about leprechauns?
Little People
Use Snots as a base, so MV 5 ST 1 AG 3 AV 5 or 6? Side step, stunty, titchy. But drop dodge and give them dauntless and mighty blow! Fighting Irish! And strength access instead of agility access? They could have trolls (if so add right stuff to the little guys), say maybe 4, drop the loner, but how about banshees? Based on Necro Werewolves but drop the frenzy and add disturbing presence. It goes against the stunty/big guy favour but would be fluffy.
My brain is a bit fried now! All I can think of are smurfs, just blue snots, but MV 6 AG 5!!! (or 4) sprint no big guys. To be in a stunty leeg what flings are in a normal BB league and, lastly, Gnomes. Like stunty dwarfs MV 4 ST2 AG 2 AV 7 block, tackle, stunty, thick skull? Strength access instead of agility access. Again no big guys.
There you go 13 stunty teams that are fluffy and not over-powered I don't think. Well tackle block Gnomes probably are! I really want a Deadfling team to play in a normal BB league!! I still would probably drop the worst three (Zombie Ogres, Undead Gobbos and Gnomes in my opinion) and have a 10 team stunty leeg.