Achievement Guide: Gelatin World Tour (Terraria)

In order to unlock the Gelatin World Tourachievement in Terraria, you need to defeat 24 different kinds of slime. There are only 25 different kinds in the game, so you pretty much need to defeat them all in order to get this achievement, and in order to do so you need both normal and hardmode games.

Below is a list of all the slime spawn locations in the normal / pre-hardmode:

Blue Slime: This slime spawns in the forest during the day. It can also be spawned with a Slime Statue.

Green Slime: This slime spawns in the forest during the day, and can also spawn in the first underground layer.

Red Slime: This slime spawns in the underground layer.

Purple Slime: This slime spawns in the farthest corners of the map, and for about 1/3 of the map towards the middle, and during the Slime Rain Event.

Yellow Slime: This slime spawns in the underground layer.

Sand Slime: This slime spawns in

Umbrella Slime: This slime spawns in the forest when it is raining.

Ice Slime: This slime spawns in the tundra layer.

Spiked Ice Slime: This slime spawns in the underground layer in the tundra.

Jungle Slime: This slime spawns in the jungle biome.

Spiked Jungle Slime: This slime spawns in the underground layer in the jungle biome.

Black Slime: This slime spawns in the cavern layer.

Mother Slime: This slime also spawns in the cavern layer. 

Baby Slime: This slime spawns when you kill a mother slime. 

Lava Slime: This slime spawns in the Underworld layer.

Dungeon Slime: This slime spawns in The Dungeon. 

Pinky: Pinky will spawn randomly in most layers, but has a much higher chance to spawn during the Slime Rain Event. There is not really a good strategy to farm him except to spam the Slime Rain event a few times.

King Slime: The King Slime will spawn at the end of the Slime Rain Event, and can also be summoned by using a Slime Crown.

And the following slimes are found in hardmode only:

Toxic Sludge: This slime spawns in the underground and cavern layers.

Crimson Slime: This slime spawns in the crimson layer.

Corrupt Slime: This slime spawns in the Corruption.

Slimeling: This slime spawns when you kill a Corrupt Slime. 

Slimer: This slime spawns inthe Corruption.

Illuminant Slime: This slime spawns in the underground Hallow.

Rainbow Slime: The Rainbow Slime will only spawn on non-hallow blocks in a Hallow-biome on rainy days.