Sam Oak

Samuel (Sam) Oak was the original professor Oak until he retired and his grandson took over his job and lab.

After he retired, he remained an active person and scientist, often helping his grandson.

During the first of Articuno's attacks on Pallet, Sam stayed back to protect the city, yet the outcome of the attack was for Delia Ketchum (Ash's mother) to get severely injured. Delia was paralyzed from the waist down, and Sam along with Gary and his wife Melissa also stayed in Pallet, refusing to give up on the city. Most of the residents abandoned it though, fearing for a second attack, which might kill them or destroy their property again.

Unbeknownst to Gary, after Delia was wounded, Sam contacted Giovanni of team rocket to help save her with team rocket's advanced medical technology. Giovanni agreed and Delia was comatose for a couple months, yet she only remained paralyzed, but she survived.

Delia was also depressed following her injury, as well as her falling out with Ash, so staying in Pallet helped brighten her mood.

During the second attack on Pallet, Gary and Melissa lured Articuno away to protect the city, while Sam and Daizy stayed behind. During that incident, Team Cipher led by Steven Stone ambushed and captured Sam, Daizy and Delia. Steven is a former champion, so he managed to defeat quite easily all fo them.

After this, Sam was taken to New Island to work for team Cipher on purification, hoping that they would be able to use this to control all cursed pokemon. Threatening to kill Delia and Daizy, Sam Oak worked for them.

At some point, he is freed and gives vital information about the world and what his research granted so far.

In the end, Oak is poisoned and dies. Then it is revealed that Delia Ketchum poisoned him and offered him to turn himself to the darkness. She says that since he isn't a trainer anymore, he can be killed without a pokemon battle. Then she reveals that she poisoned him and he only has limited time until he accepts the darkness. If he does, she will give him the antidote. Oak refuses, he lays paralyzed for a while, until even his lungs are paralyzed and he can't breath. Delia Ketchum looks into his eyes as he dies, in agony but unable to show it. His body is found the next day by Gary. Since the attack on Saffron is imminent, Ash pleads with Gary to turn his pain in anger and use it for the attack.