Hiya,
It's always like that...They will preview what will come in the future sets..Like in Hidden legends, there's Totodile, Chicorita, and Cyndaquil and non of their evolutions, previewing Unseen forces. and in TMTA, there's Bulbasaur, Squirtle, and Charmander, and non of the evos, previewing FRLG. There's more stuff like this...
cya.