These are the particles that could represent some of the spirit subtypes types. (
@owlcool)
Ocean: any water particle or thing like that really,
Swamp: slime particles
Moon: Snowball particles
Sun: yellow wool breaking particles
Animal: creeper could use explosion, endermen could be portal particles, etc.
Wisdom: Enchantmenttable particles
Helping: heart(You got better idea?)
Order: barrier
Chaos: purple redstone particles
Koh: AngryVillager
Chicken: White wool breaking particles
Cow: both white and blackwool breaking particles
Zombie: a ugly green color, preferably around the head area, by ugly green I mean dark green, like dark green blocks have.
Skeleton: spawns a arrow entity every few seconds nearby.
Creeper: explosion particles
Guardian: needs work, but maybe something like fishing particles nearby.
Cave Spider: Splash potion poison particles
This is not all the spirits, if you have any suggestions, suggest them