How migrate VM guest machine from ESXi3 to ESXi5 without any vCenter?

VMs can be migrated from one host to another with vMotion technique. vCenter is just an interface. So, there is no need of vCenter.

I will provide you three methods.

1. Through VMware vCenter Converter client. Use the option powered on machine.

2. Shut down the VM. Copy the VM folder to a datastore that is visible to ESXi 5 host. Remove the VM from ESX 3 inventory. Then browse the datastore and go to the VM path. At last, right click on the .vmx file and click add to inventory.

3. Shutdown the VM. Copy the .vmdk file to a datastore visible to ESXi 5. Create new VM on ESXi 5 host and use the copied vmdk file as it hard disk instead of creating new one.