Some ideas on possible Necrozma forms

Cosmog Unaware 43 29 31 29 31 37
#790
Cosmoem Sturdy 43 29 131 29 131 37
#791
Solgaleo Full Metal Body 137 137 107 113 89 97
#792
Lunala Shadow Shield 137 113 89 137 107 97
#800
Necrozma Prism Armor 97 107 101 127 89 79

As seen here, much like Type: Null's speed, Necrozma's speed stat is inverted.

If we return it to Lunala/Solgaleo standards, we get:

97 107 101 127 89 97

Total: 600+18= 618

If we return its HP to regular standard as well:

137 107 101 127 89 97

Total: 618+40=658

If we return its Defense to 113 as well.

137 107 113 127 89 97

Total: 658+12= 670

Alternatively, if we take its Sp. Defense to Defense level:

147 107 101 127 101 97

Total: 658+12= 670

If we take its Sp. Attack to Lunala level:

137 107 113 137 89 97

or

137 107 101 137 101 97

Total: 670+10 = 680

The alternate scramble of this would be:

137 137 89 107 113 97

or

137 137 101 107 101 97

To make both offenses we would need 30 more BST.

137 137 113 137 89 97

or

137 137 89 137 113 97

or

137 137 101 137 101 97

Total: 680+300=710

Some other distributions can also include

147 117 101 117 101 97

Total: 680

147 127 91 127 91 97

Total: 680