The 5* getting upgraded in the Shida patch are:
Magma God Agni
LS: Increases ATK of all units by 25% and reduces damage from Earth element by 15%
BB: 16 combos fire element to one enemy (400%)with chance to inflict injury (80%) (15 BC)
SBB: 21 combos fire element to all enemies (450%) with chance to inflict injury (80%) and increase BB gauge for 3 turns (4 BC/turn) (38 BC)
Lord stats: 6163 | 1933 | 1653 | 1420
IMP stats: +750 | +300 | +300 | +300
Normal hit: 12 hits (24 max BC generated)
Ice Winged Knight Sergio
LS: Increases ATK of all units by 25% and reduces damage from Fire element by 15%
BB: 15 combos water element to one enemy (350%) with a chance to inflicts weakness (80%). (13 BC)
SBB: 17 combos water element to one enemy (600%) with a chance to inflicts weakness (80%) & completely refills his SBB gauge (100%). (43 BC)
Lord stats: 6037 | 1805 | 1720 | 1720
IMP stats: +750 | +300 | +300 | +300
Normal hit: 12 hits (24 max BC generated)
Holy Earth Empress Lidith
LS: Increases ATK of all units by 25% and reduces damage from Thunder element by 15%
BB: 18 combos earth element to one enemy (400%) & increase HC drop rate (100%). (15 BC)
SBB: 22 combos earth element to all enemies (450%) & increase HC drop rate (70%) & prevents status ailments for 3 turns. (30 BC)
Lord stats: 5822 | 1860 | 1521 | 1959
IMP stats: +750 | +300 | +300 | +300
Normal hit: 13 hits (26 max BC generated)
Heaven Sky God Falma
LS: Increase ATK of all units by 25% and reduce damage from Water element by 15%.
BB: 15 combos thunder element to one enemy (400%) with chance to paralyze (80%). (15 BC)
SBB: 19 combos thunder element to all enemies (450%) with chance to paralyze (60%) and greatly increase atk, def, and rec to all allies for 3 turns (70%). (40 BC)
Lord stats: 6000 | 1884 | 1632 | 1654
IMP stats: +750 | +300 | +300 | +300
Normal hit: 11 hits (22 max BC generated)
Holy Gun Emperor Heidt
LS: Increases ATK of all units by 25% and reduces damage from Dark element by 15%
BB: 20 combos light element to one enemy (400%) and increase BC & HC drop rate (50% BC & 30% HC) (15 BC)
SBB: 20 combos light element to all enemies (450%) and increase BC & HC drop rate(50% BC & 30% HC) and add ignore defense to all allies for 2 turns (100%). (40 BC)
Lord stats: 5951 | 1932 | 1848 | 1431
IMP stats: +750 | +300 | +300 | +300
Normal hit: 15 hits (30 max BC generated)
Eradicator Shida
LS: Increases ATK of all units by 25% and reduces damage from Light element by 15%
BB: 25 combos dark element attack to all enemies (400%). (34 BC)
SBB: Adds all elements to all allies for 3 turns and increases BB gauge(10 BC increase). (46 BC)
Lord stats: 5904 | 1901 | 1595 | 1822
IMP stats: +750 | +300 | +300 | +300
Normal hit: 13 hits (26 max BC generated)
So make sure you really dont want those crappy old units before fusing them away.
From:
Shida Batch 6* unit info and analysis. (Always updating edition) | Brave Frontier Forumhas some analysis too.