TheWertle has retrieved the Boss HP information from the Kingdom Hearts II: Final Mix+ Ultimania Book for Kingdom Hearts II and Kingdom Hearts II: Final Mix. I presume these are the values on the Standard difficulty:

Kingdom Hearts II

Twilight Thorn – 300
Axel 1st time – 105
Axel 2nd time – 345
Vivi Illusion – 1
Shadow Roxas – 105

Shan-Yu – 442
Hayabusa – 102

Beast – 156
Thresholder – 137
Possessor – 98
Shadow Stalker – 176
Shadow Thorn – 390

Hades
1st time – 660
2nd time – 660
3rd time – 1230
4th time – 1230
Goddess of Fate Cup – 1575
Paradox Hades Cup 1st time – 2715
Paradox Hades Cup 2nd time – 2715

Cerberus
1st time – 440
Cerberus Cup – 960
Paradox Cerberus Cup – 1995
Paradox Hades Cup – 2715

Demyx 1st time – Not Applicable
Water Bodies – 3 each
Hydra – 462

Pete
1st time – 264
2nd time – 264
Timeless River Past Pete – 123
3rd time – 123
4th time – 784
Paradox Hades Cup – 2896

Barbossa – 612
Illuminator – 26

Volcano Lord & Blizzard Lord
Volcano Lord – 351
If Port Royal Episode 2 has been cleared first – 527
Paradox Hades Cup – 2172
Blizzard Lord – 351
If Port Royal Episode 2 has been cleared first – 527
Paradox Hades Cup – 2172

Prison Keeper – 1140
If Port Royal Episode 2 has been cleared first – 1640
Oogie Boogie – 371
If Port Royal Episode 2 has been cleared first – 533

Hyenas 1st time – 305
If Port Royal Episode 2 has been cleared first – 430
Hyenas 2nd time – 445

Scar – 915
If Port Royal Episode 2 has been cleared first – 1290

Hostile Program – 640

Demyx 2nd time – 1005
Water Bodies – 5 each

Mysterious Man – 760
Storm Rider – 1216

Xaldin – 1155

Grim Reaper 1st time – 790
Grim Reaper 2nd time – 790

Jafar – 840

Lock, Shock and Barrel – 172 each
Test Subject (Experiment) – 1290

Ground Shaker – 1424

Sark 1st time – 460
MCP – 920
Sark (with MCP)- 230

Leon
Pain and Panic Cup – 357
Paradox Pain and Panic Cup – 819
Paradox Hades Cup 1st time – 1267
Paradox Hades Cup 2nd time – 634

Yuffie
Pain and Panic Cup – 255
Paradox Pain and Panic Cup – 585
Paradox Hades Cup 1st time – 905
Paradox Hades Cup 2nd time – 453

Tifa
Paradox Hades Cup 1st time – 1086
Paradox Hades Cup 2nd time – 1086
Paradox Hades Cup 3rd time – 543

Cloud
Paradox Hades Cup 1st time – 1448
Paradox Hades Cup 2nd time – 1448
Paradox Hades Cup 3rd time – 724

Hercules
Titan Cup – 1290
Paradox Titan Cup – 2250

Sephiroth – 3000

Xigbar – 1300
Luxord – Time Gauge replace HP
Card – 50
Saïx – 1500

Xemnas
1st time – 1500
Armoured 1st time – 1000
Armoured 2nd time – 1000
Dragon Left Part – 1200
Dragon Right Part – 1500
Floating Mine B – 100 (80 exp)
Spider B – 100 (80 exp)
Missile B – 100 (80 exp)
Xemnas 2nd time – 1500

Kingdom Hearts II: Final Mix

Roxas (Main Story) – 1300

Absent Silhouettes

Zexion – 708
Larxene – 1065
Vexen – 1500
Shield – 100
Clone Level 1 – 100
Clone Level 2 – 160
Clone Level 3 – 250
Clone Level 4 – 350
Clone Level 5 – 450
Lexaeus – 1578
Marluxia – 2817

Data Battles

Xemnas 1st time – 3400
Xemnas 2nd time – 3400
Xigbar – 2896
Xaldin – 3400
Vexen – 2715
Shield – 181
Clone Level 1 – 181
Clone Level 2 – 290
Clone Level 3 – 453
Clone Level 4 – 634
Clone Level 5 – 815
Lexaeus – 3400
Zexion – 2172
Saïx – 3400
Axel – 3400
Demyx – 2715
Luxord – Time Gauge replaces HP
Card – 91
Marluxia – 3400
Larxene – 2715
Roxas – 3168

Terra (Enigmatic Soldier/Secret Boss) – 3400