True Pacifist Ending Credits

Upon completing the Pacifist Route, the player will be subject to credits featuring all of the enemies of the game, and then a bullethell section in which you must dodge the names of all the kickstarter backers. If you successfully dodge all of the names, you will be able to access the mysterious door in Snowdin Forests. The description of each enemy in the game will be yellow depending on whether or not you took certain actions while in battle with each enemy.

How to get a yellow description for each enemy in the credits.
Froggit: Compliment.

Whimsum:

Moldsmal: Flirt.

Loox: Don't Pick On.

Vegetoid: Dinner, and then grab the green vegetable.

Migosp: Talk to him after sparing all other enemies.

Napstablook:

Snowdrake: Wait a turn, and then laugh at his pun.

Icecap: Ignore him twice, steal his hat, then compliment him.

Gyftrot:

Doggo: Pet him.

Dogamy & Dogaressa: Roll around, re-sniff, then pet them both.

Lesser Dog: Pet him. A lot.

Greater Dog:

Aaron: Go to Napstablook's house in Waterfall, play any of his songs, then leave and enocunter an Aaron.

Moldbygg: Unhug.

Woshua: Ask to be cleaned, get the green.

Temmie:

Mad Dummy:

Shyren: Hum enough times as to finish your musical career.

Vulkin: Hug or encourage.

Tsunderplane: Approach, and touch the green enough.

Pyrope: Turn up the heat twice.

Muffet:

Royal Guards: Polish 02's armor, whisper to 01.

Final Froggit: Mystify.

Whimsalot: Pray.

Astigmatism: Pick on him.

Madjick: Stare twice.

Knight Knight: Sing.

Anamganates: Spare them, don't throw the stick.

Trivia

 * Jerry does not appear in the credits.