The complex, $\left[Pt\left(py\right)\left(N{H}_3\right)BrCl\right]$ will have how many geometrical isomers?

The complex is square planar and is of the type [M(abcd)]. It has three geometrical isomers.

For linkage isomerism, presence of ambidentate ligand is necessary.
For coordination isomerism, both the cation and amon of the complex must be complex ions.
For ionisation isomerism, an amon different to the ligands must be present outside the coordination sphere. All these conditions are not satisfied by this complex. Hence, it does not exhibit other given isomensms