[Soumi]

Alright first of all, you'll need to create some vehicle around the sumo map. then create some variables like this:

pawn Код:

//On the top of your script
//if you have 6 cars
new IsCar0Used;
new IsCar1Used;
new IsCar2Used;
new IsCar3Used;
new IsCar4Used;
new IsCar5Used;

Then...

pawn Код:

//Under OnGameModeInit()
IsCar0Used = 0;
IsCar1Used = 0;
IsCar2Used = 0;
IsCar3Used = 0;
IsCar4Used = 0;
IsCar5Used = 0;

and now the in the /sumo command

pawn Код:

//Follow this:
if(IsCar0Used == 0)
{
    PutPlayerInVehicle(playerid, 0, 0);
    SendClientMessage(playerid, 0x33AA33AA,"Welcome in (/Sumo)!.");
    IsCar0Used = 1;
}
//Do the same thing with the other vehicles :D

If u need more explanation tell me.