  We have performed N-body simulations of poor clusters with enough particles
to resolve the individual galaxies. The main cases of initial conditions are:
(i) 50 equal mass galaxies; (ii) 60 galaxies with masses drawn from a Schechter
distribution function, and (iii) the collision of two subclusters each one
containing 25 galaxies. The evolution and kinematics of the first ranked
galaxy, the substructures, and the possible rotation of clusters are
investigated. A massive object with cD characteristics is always formed and is
never found farther than 100 kpc from the centre of the cluster. This massive
galaxy oscillates around the cluster centre with an average peculiar velocity
of 70 km s$^{-1}$. We show that increasing the initial intra-cluster medium
(ICM) mass while keeping the galaxies mass and structure without change, raises
the merging rate due to the dynamical friction with the ICM. Substructures are
almost always present on the galaxy count contour plots. The ICM projected
density, which should be similar to the X-ray emission map, presents strong
substructures when we have colliding subclusters. Otherwise, in isolated
clusters, the substructure is less pronounced indicating that substructures
should reflect important but transient dynamical phenomena. We propose that
clusters formed by an off-centre collision and subsequent merging of two
approximate equal mass subclusters should show a general rotational pattern
that could be detected even after the relaxation of the cluster. These clusters
would have a spin parameter, $\lambda$, of about 0.3-0.5.
