  We give the detailed analysis of effects of flavor dependence of average
transverse quark momentum inside a meson on J/psi --> P and \Upsilon --> Bc
transition form factors and two-body weak hadronic decays of J/psi and \Upsilon
employing the factorization scheme. We predict the branching ratios of
semileptonic and nonleptonic weak decays of J/psi and \Upsilon mesons in
Cabibbo-angle-enhanced and Cabibbo-angle-suppressed modes.
