Yes, if you have lease done for your plot, you can sale and get it transferred in the name of buyer as transfers are open for a residential plots in 2009 scheme for Sector 18 & 20 as per now (Oct 2019).
All plots allotted by Yamuna authority are on lease hold. The 3 authorities in Gautam Budh Nagar 1) Noida Authority 2) Greater Noida Authority and 3) Yamuna Authority does allotment of plots on lease hold for 90 to 99 years which means they remains owner of the land and they allot land to allottee on rent and charges lease rent against it. Residential land in Gautam Budh Nagar is leased by these authorities for a period of 90 years. Lease properties can’t be divided into smaller pieces.
All plots allotted in 2009 were unregistered once. When Yamuna authority develop any plot it is unregistered. Unregistered doesn’t mean it is unauthorised. Unregistered simply means registry is not done yet. Once authority give allotment, it develop plot with all facilities like roads, sewerage, electricity, water pipeline and does demarcation of the plot. Then authority sends offer of possession to allottees. Allottee then execute the registry (lease deed) and plots get registered and called registered plot.
All Gautambudh Nagar allotted properties are lease hold properties. For these the lease rent for 90 year or 99 years at some places needs to be paid. In YEIDA one time lease rent for 90 years to be paid to authority. It is 10% of the allotment cost. This is paid at the time of possession for all YEIDA plots. The lease rent needs to be paid at the time of possession. When YEIDA sends allottee offer of possession, it adds lease rent in possession time charges.