Usually you will neither use VLAN1 (native VLAN by default) nor VLAN 4095 (special purpose) or any reserved Cisco VLAN's when you work with trunk ports in ESXi. You can however use any other VLAN, which you may need to allow on the physical trunk port(s). The VLAN-ID will be added and/or removed - by the port group on which it is configured - to/from the network package (like on an access port).
André