All the statistical tests available in Brainstorm are described in this tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials/Statistics
If you want to do the statistical analysis outside of Brainstorm, you can export the values you want to compare to Matlab or as .nii/.gii or text files, depending on the type of data it is.
For instance, the tutorials below illustrate how to export source results to SPM:
https://neuroimage.usc.edu/brainstorm/ExportSpm8
https://neuroimage.usc.edu/brainstorm/ExportSpm12