I didn't play much at all this playtest but I often did end up playing you with Duggy + Sun and it really did threaten you. I was able to trap Heatran with Duggy, and then bring in Morning Sun Volcarona on Reuniclus and force a win from there.
There is not really much you can (or could) do about this since after I trap Tran, you do struggle against it, especially as Mollux, Tar and Tran are all easily trapped by Duggy. Just a quick fix I could recomend is running Psyshock over Psychic on Reuniclus. A +1 Psyshock would hurt the fuck out of Volcarona and basically means that it cannot risk staying in too long against you. Its a small change, but I think it would just give you a little more of an edge against sun.
Just something to consider.