Ghetsis first appears giving a speech in Accumula Town urging people to release their Pokémon. Publicly he is one of Team Plasma's Seven Sages, but after the player defeats N at N's Castle he reveals that he raised N as a tool and that the liberation campaign was a lie: he wanted to be the only person in Unova with Pokémon. He then battles the player with Cofagrigus, Bouffalant, Seismitoad, Bisharp, Eelektross and a level 54 Hydreigon. That fight makes him the final main opponent of the game and, per Bulbapedia, the first final opponent in a core series game who is not a Champion.
In Black 2 and White 2 he is revealed as the mastermind of the new Team Plasma. At the Giant Chasm he uses the DNA Splicers to fuse Kyurem with Zekrom or Reshiram, then fights the player himself. An alternate-world Ghetsis also joins Team Rainbow Rocket in Ultra Sun and Ultra Moon.
In the anime he is the main villain of the Episode N arc, directing Colress's Pokémon control experiments and using the device to seize Reshiram before his plan collapses and he is arrested.
His card is a Team Plasma Supporter from Plasma Freeze (2013): a Rare at #101 illustrated by Yusuke Ohmura, and a full-art Ultra Rare at #115 illustrated by Kanako Eo. It makes your opponent reveal their hand and shuffle every Item card in it back into their deck, then you draw one card for each Item shuffled away. The card has been banned in the Expanded format since August 17, 2018.
The Rare Team Plasma Supporter, illustrated by Yusuke Ohmura.
The full-art Ultra Rare version, illustrated by Kanako Eo.
Yes. He is its true mastermind and one of the Seven Sages, while presenting his foster son N as its figurehead leader in Black and White.
In Black and White: Cofagrigus, Bouffalant, Seismitoad, Bisharp, Eelektross and Hydreigon. In Black 2 and White 2 he first makes the player face his fused Kyurem, then battles with Hydreigon alongside Drapion, Toxicroak and others.
Your opponent shuffles every Item card in their hand into their deck, and you draw a card for each one. It is banned in Expanded.

VILLAIN
2 Trainer cards · 0 partner Pokémon
Ghetsis is one of Team Plasma's Seven Sages and the true mastermind behind the team in Pokémon Black and White and Black 2 and White 2, using his foster son N as a figurehead. His Team Plasma Supporter card was printed in Plasma Freeze (2013).
No published index yet — too few of Ghetsis’s cards trade often enough to strike one.