Here's an imgur album I uploaded to show their 3* forms and their 4* forms

Quote from /u/miriverite -

"As y'all may know, JPBF got a new quest map. Here are some of the farmables you can find there :) details are for 4-star versions.

Gorutoba (Fire)

• LS: 15% less damage from Earth units

• BB: 8-hit Fire (SGT) / Add Fire element to attack for 3 turns

Yeiga (Water)

• LS: 50% increase in ATK, DEF, and REC for 1st turn

• BB: 6-hit Water (AOE) / DEF Ignore for 2 turns

Risuteraru (Earth)

• LS: Large chance of BB gauge fill upon enemy defeat

• BB: 7-hit Earth (SGT) / chance Paralysis

Raiden (Thunder)

• LS: 30% increase in HP and REC if 5 or more elements present

• BB: 9-hit Thunder (AOE) / chance Injury, Weakness

Mira (Light)

• LS: 50% increase in ATK when BB gauge is full

• BB: 7-hit Light (AOE) / increased HC drop rate for 3 turns

Haaveru (Dark)

• LS: 50% increase to DEF for Dark units

• BB: 8-hit Dark (SGT) / half DEF to increase ATK for 3 turns"