Board Thread:General Discussion/@comment-37186143-20181230043958/@comment-38065687-20190105221613

Note: Living Asriel plus human soul ALSO gave "adult" Azzy, with great power. Flowey had neither a monster body nor soul, though - bit of a handicap.

I guess no more than one soul can be absorbed naturally. The lab machines were designed to allow 7, the only number they cared about - humans made the Barrier with 7, incidentally maybe some special threshold value for SuperPower.

With just 6, Flowey remains reliant on the DT extractor (seen in the middle), limiting his choices of form.

Don't question the Monsters' science, they could prod timespace ;)