Well,
@LuisCarlos17f 's question did give me a though. You can use this to create 3e style templates.
Lets see if it works reasonably well.
Half Dragon
+4 strength, +4 intelligence, +4 charisma, +4 constitution
+2 AC (scales)
Size grows by 1 (HD increase)
Fly speed equal to your ground speed
Magic resist if CR 9, or could already fly.
Immune to one element type, resistant to another (depending on dragon breed)
Bonus action breath weapon (1d8 damage per 2HD (round up), Charisma-based DC, area large enough to hit 2 creatures, recharge 6)
Divide HD by number of attacks and divide by 3; round down. Gain that many 1d6 elemental damage on your attacks.
+2 damage/tap if strength based
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I'll assume +2 to your primary stat (2 MBP)
+2 AC (2 MBP)
Fly speed (2 MBP if CR 9 or under) or magic resist (2 MBP if CR 9 or higher)
+2 HP/HD (0.25 MBP/HD)
HD grows by 1 (1 HP/HD) (0.125 MBP/HD)
9 bonus damage per 2HD (0.5 MBP/HD)
3.5 DPR for every 3 HD (0.4 MPB/HD)
2 DPR/tap (2-6 MBP)
Total: about 1.25 MBP/HD
Total: 8-12 MBP plus 1.25 MBP/HD.
But multiple attacks correlates with more HD, so...
CR impact: +2 CR, +1 for every 3 HD.
...
Half-red dragon griffon. 7HD: so CR 2+2+7/3 =
CR 6.
Huge Draconic Beast
14 AC
22 strength
20 constitution
12 charisma
7d12+35 HP (80 HP)
Magic resistant
Immune to Fire
Resistant to Cold
Beak: Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 6) piercing+ 3 (1d6) fire damage.
Claws: Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing + 3 (1d6) fire damage.
B
onus Action Breath Weapon: DC 12 dex save for 4d8 (18) fire damage (save for half)
...
It does constrain the template design if you want it to be able to calculate CR changes without basically rebuilding it.