The CDW strengths in quasi-one dimensional halogen-bridged Pt, Pd and Ni mixed-valence compounds, [M^II(AA)₂][M^IVX₂(AA)₂]Y₄ are tuned by substituting the constituent metal ions, bridging halogens, in-plane ligands, and counteranions. Relaxation processes from the excited states, dynamics of solitons and polarons, and third-order nonlinear optical properties depend on their CDW strengths. The SDW strengths in [Ni^III(chxn)₂X]Y₂ are tuned by substituting bridging halogens and counteranions. These compounds are not Mott-insulators but Charge-transfer-insulators. The competition between the CDW states in Pd^II-Pd^IV sites and the SDW states in Ni^III sites in the Ni-Pd mixed-metal compounds, Ni₁-xPdx (chxn)₂Br₃ are investigated. As a result, the Pd^II-Pd^IV states are approaching to the Pd^III states, because of the stronger on-site Coulomb interaction in Ni^III sites.