The complex that shows Facial - Meridional isomerism is:

Facial-Meridional (fac-mer) isomerism occurs in octahedral complexes of the type $$[MA_3B_3]$$, where three identical ligands can either occupy the same face of the octahedron (facial) or be arranged along a meridian (meridional).

Let us analyze each option:

Option 1: $$[Co(en)_2Cl_2]^+$$ - This is of the type $$[M(AA)_2B_2]$$, which shows cis-trans isomerism, not fac-mer isomerism.

Option 2: $$[Co(en)_3]^{3+}$$ - This is of the type $$[M(AA)_3]$$, which shows optical isomerism only.

Option 3: $$[Co(NH_3)_3Cl_3]$$ - This is of the type $$[MA_3B_3]$$, which is the classic case for facial-meridional isomerism. The three $$NH_3$$ (and three $$Cl$$) ligands can be arranged in either fac or mer configuration.

Option 4: $$[Co(NH_3)_4Cl_2]^+$$ - This is of the type $$[MA_4B_2]$$, which shows cis-trans isomerism.

The correct answer is Option 3: $$[Co(NH_3)_3Cl_3]$$.