Assuming that by "rotation speed of galaxies in a galaxy cluster" you mean something like orbital speeds (since most galaxies in a cluster have rather radial orbits and don't "rotate" within the cluster):
Yes, you absolutely need extra dark matter in the cluster, outside of the dark matter in the individual galaxies. The mass in a cluster comes primarily in three forms:
- Ordinary (baryonic) matter in galaxies, mostly in stars (about 1-2% of the total mass);
- Baryonic matter in the form of thin, extremely hot gas in between the galaxies, filling the cluster (about 10% of the total mass);
- Dark matter (about 85+% of the total mass).
If you assume that each individual galaxy has dark matter amounting to about 10 times the baryonic matter (as is the case for most galaxies, including the Milky Way), then the per-galaxy dark matter is only about 10-20% of the total mass. Given that the total dark matter content is about 85% or more, that means $\sim 70$% of the total mass is in the form of dark matter filling the cluster in between the galaxies.