Swampert Crest: Boosts water and ground type moves and applies aqua ring for 3 turns upon entry.
Heracross Crest: if the ability is swarm Boosts its attack at half health instead of 1/3.
If the ability is guts if burned raise attack by 100% instead of 50% and if poison, heal from it ever other turn.
If ability is moxie raise both attack and special attack stat by 1 upon entry. and boosts bug type moves regardless of ability.
Parasect Crest: Apply sleep to enemy for 1 turn upon entry and boost grass and bug moves.
Swoobat Crest: Apply Mind Reader upon entry and boost psychic types moves.
Lycanroc Crest: Apply stealth rock up entry and boost rock type moves.
(Hope you like them.)