>>24591972The trend I noticed is that the eeveelutions' typings are those which attacks were considered "special" before the physical/special split in gen 4.
Before gen 4, Water, Grass, Fire, Ice, Electric, Psychic Dragon and Dark moves were considered special. Normal, Flying, Fighting, Ground, Rock, Bug, Ghost, Poison and Steel moves were considered Physical.
The only exceptions would be Fairy type (since it didn't exist pre gen 4) and Dragon type, since there hasn't been a Dragon type eeveelution (maybe next gen?).