Omg, I have that problem way too much. I am usually on F, but like some frames are synchable, and others are preset. Its a pain in the ass I swear.
I had to fo 76 PID advancements, just to find the right synchable Frame for a Klink. Such a major pain lol. :)
Good Luck, victini was done on my first try. Im gonna go for an adamant Pawniard, and shiny jolly Rufflet. Then Terrakion, Virizon, and kurem. :) then restart! Lol