I don't believe your code is doing what you intended.
There is no definition of T0, so I made up one.
T0 = Table[x^int, {int, 1, 3^4}]
pret00 = Table[T0[[int]]*LegendreP[0, Cos[x]]*Sin[x], {int, 1, 3^4}]
Now to check and see if Integrate is doing something sensible:
Integrate[pret00[[1]], {x, 0, Pi}]
Yes, it is. So, something like this gives sensible results
ParallelTable[Integrate[pret00[[int]], {x, 0, Pi}], {int, 1, 12}]
or
ParallelTable[Integrate[pret00[[int]], {x, 0, Pi}], {int, 1, 3^4}]
which will produce fairly long output, but you can view it all if you wish.
However, I believe the Table that you have inside ParallelSubmit isn't doing what you expected because you are looking for the 0 index of a list, which will be "List".
ParallelTable[Integrate[pret00[[int]], {x, 0, Pi}], {int, 0, 1}]
A quick look at the ParallelSubmit documentation shows that the result of ParallelSubmit is a List of objects which are ready for computation on the kernels, but computation doesn't start until WaitAll or WaitNext is executed