Sonic & All-Stars Racing Transformed

To get this achievment just play in Time Attack mode on any race where you can do at least one Stunt Combo. A Stunt combo is when you push the right analog stick in any direction while in mid air to do a trick, land successfully and go straight into landing another trick.

Time attack lets you play indefinitely unless you press Y to quit so just keep playing until you have done 10 combos. There are also no NPC racers hitting you and throwing you off track so landing the combos should be easier. You can also go for beating all the staff ghosts on a particular level while getting this achievement.

I got this on Ocean View with Reala by taking the first boost pad you come across up the hill and tricking in the air, then after bouncing off the hill doing another trick before landing at the bottom.

Perhaps the best track would be Samba Studios as there are several places to get combos from.
First - last 2 ramps at the end of the first boat section. Also you can trick at the waterfall when you transform back into a car for an 'Awesome combo' - although I don't know if this would count as two combos, it at least gives another chance in case anything goes wrong.
Second - as you transform into the boat for the second time do a trick and aim for the right side (left on mirror) to hit the ramp for the combo.
Third - immediatly after the ramp described above, there is a corner and a ramp straight after. Hit this ramp and the one further ahead and you have a combo. You can also trick when you transform back into a car for a possible 'Awesome Combo'.

Other tracks where I have previously done combos:
Dream Valley - 3rd section where you are going down waterfalls in boat form.
Graffiti City - Across some rooftops after passing through a building near the start of the lap. I find taking the right fork in the roof (left on mirror) is easier but both can be used to trick.
Adder's Lair - Take the lower path just before the boat section then trick down the lavafall and aim for the ramp for the next trick.
Shibuya Downtown - Before the final corner there are two jumps that can be tricked off of.

There are probably more places but these are the only ones I can remember right now.

Start up your game with 2 controllers plugged it and go to CUSTOM GAME then select LOCAL.

Next go to the second game mode called BATTLE ARENA and from here select NEON DOCKS.

Smaller characters with smaller cars is better but all can do the stunt combos. I used PUDDING

When the game starts turn around and there is a RAMP on the BACK WALL. Do a stunt off the BACK RAMP and you will see 2 RAMPS in the MIDDLE, do the second flip off one of these ramps (which ever side you are on). You will get a combo doing this method and just RINSE AND REPEAT 10x.

There is a time limit but you will not need the whole time.

EDIT: If negative please indicate why to help better the solution. Thanks

EDIT 2: This achievement has been buggy for some players. You might need to try more than 10x to get achievement.

EDIT 3: I managed to unlock it first try by removing the title update and played offline in a fresh game. -oGARY86-