These are achievements that have to do with pokemon you've seen.

Mega Evolution Successor-Collect every Mega capable Pokémon.

Opposite Evolver-Get a mega evolution exclusive to the opposite version.(Example:Mega Charizard Y in X.)

Prehistory n the Making-Have every fossil pokemon.

Flaming kickoff-Obtain every fire starter.

Tidal kickoff-Obtain every water starter.

Nature Kickoff-Obtain Every Grass Starter

Dragon Master-Obtain every Dragon Type pokemon.

Lucky Color-Collect a Shiny Pokémon.

Sparkly...-Obtain 5 Shiny Pokémon.

TOO MANY SPARKLES-Obtain 15 Shiny Pokémon.

Y'ddgrasil Trio-Obtain Xerneas,Yveltal and Zygarde.

Yin,Yang,Yo-Obtain Reshiram,Zekrom and Kyurem.

CREATION POWER-Obtain Dialga,Palkia, And Giratina.

Water,Earth,Air-Obtain Kyogre,Groudon and Rayquaza.

Tower Time-Obtain Ho-Oh and Lugia.

Kenesis killed the Cat-Obtain both Mew and Mewtwo. What up,God?-Obtain Arceus.