>>55895559For Jolteon, since it's main skill is unremarkable, the preference is to go for BFS and helping speed boosts instead since it has a remarkably high helping speed.
This makes it a good pick for a Raikou team, where Raichu is the best berry gatherer, Ampharos is a great Charge Strength M user, and Dedenne's Extra Tasty S use really helps with cooking crits.
(There are still no electric ingredient specialists).
There's no saving Umbreon because it's main skill recharges its own energy, which only makes sense for Berry or Ingredient specialists who can actually deliver on gathering strength directly.
Umbreon is outclassed by all other dark types in some way.
Pic related are the most relevant Eeveelutions spec'd as BFS helping speed focused, or Skill Trigger focused (without main skill level ups).
You can substitute Flareon for Glaceon, they're about the same with the same main skill, though Glaceon is slower with stronger berries.