Elastic Allocation Pools only plays a role for you as a provider, where and how the resources are allocated (on VM level or RP level for example).
And also the CPU guarantee value is only for you as provider to overcommit the CPU resources. If you guarantee 10%, in vSphere only 10% of the used CPU resources will be set as reservation. But for the customer it looks like 100%. So, if the CPU ressources are completely used the customer can not power on any further VMs.
As an example:
1 GHz CPU speed, allocation pool with 12 GHz and 10% CPU guarantee. The customer configures VMs with 12 vCPUs.
In the vCD GUI the customer now sees that 100% of the CPU resources are in use. But in vSphere only 1.2 GHz are reserved for the customer. So you as a provider can overbook the CPU resources. That's the advantage of the allocation pool in contrast to the reservation pool model where all resources are bound to the customer.