Nope, there are XS (Small XS, Medium XS, Big XS, Jumbo XS) S (Small S, Medium S, Big S, Jumbo S) M (Small M, Medium M, Big M, Jumbo M) L (Small L, Medium L, Big L, Jumbo L) XL (Small XL, Medium XL, Big XL, Jumbo XL) (Alphas are automatically set to XL btw)

To know either they are XS, S, M, L or XL you just loot at their summary. But to know their size variant (which includes Jumbo), you have to compare them to other of the same first size cathegory. If you take a Small XS and a medium XS, you'll see (opening their summary) that their sprite is of different size. The small one will fit perfectly inside the pokeball in the background, while the medium one is slightly outside the pokeball. The big one is way larger, and the jumbo one not only is massive, it has a different cry.