Despite being in Standard sets, these cards are explicitly not allowed in Standard decks.
Standard is a rotating group of Magic: The Gathering sets. Most sets enter Standard when they're released and drop out about twenty-one months later.
Generally Standard will grow until it would receive its ninth set, then instead it drops its oldest four sets to receive it as a fifth set. There are exceptions to this. It's confusing.
A Standard card is a card printed or reprinted into a set currently in Standard.
A Standard deck contains only Standard cards (60+ of them), can optionally have a sideboard of up to 15 more Standard cards, and apart from basic lands does not have more than four copies of any one card .
Brawl is a format based on Standard—all rotations listed here apply to Brawl—but Brawl has a separate banlist.
Not all sets enter Standard upon release. For example, Masters sets and Commander sets do not enter Standard.