  We present an upgraded version (denoted as version 2.0) of the program
HELAC-Onia for the automated computation of heavy-quarkonium helicity
amplitudes within non-relativistic QCD framework. The new code has been
designed to include many new and useful features for practical phenomenological
simulations. It is designed for job submissions under cluster enviroment for
parallel computations via Python scripts. We have interfaced HELAC-Onia to the
parton shower Monte Carlo programs Pythia 8 and QEDPS to take into account the
parton-shower effects. Moreover, the decay module guarantees that the program
can perform the spin-entangled (cascade-)decay of heavy quarkonium after its
generation. We have also implemented a reweighting method to automatically
estimate the uncertainties from renormalization and/or factorization scales as
well as parton-distribution functions to weighted or unweighted events. A
futher update is the possiblity to generate one-dimensional or two-dimensional
plots encoded in the analysis files on the fly. Some dedicated examples are
given at the end of the writeup.
