The following Spells/Features require use of the DM Basic Rules
- Features: Elemental Wildshape
- Spells: awaken (only if plant), conjure celestial, conjure elemental, conjure minor elementals, create undead (ghoul), and planar ally (only if celestial or elemental, as the Imp and Quazit are in the PHB)
All other Spells/Features are limited to the options in the PHB/MM.
This includes (but is not limited to)
polymorph, shapechange, find steed, true polymorph, conjure woodland beings (sprite only), conjure fey, gate, wildshape, etc.
Sadly, this means nobody will be shapechanging into a dragon as there are no dragons (other than pseudodragon)
in the PHB/MM Appendix A.