Extending AMO techniques of motional control to heavy polyatomic molecules opens new possibilities for precision measurements of fundamental physics. Though various laser-cooling and deceleration techniques have been applied to diatomic molecules throughout the last decade, their application to more complex molecules has heretofore been focused on light species, leaving generalizability to heavy species an open question. To investigate the high-mass frontier, we here study how to extend motional control to heavy-atom-containing polyatomic molecules. First, we discuss Zeeman- Sisyphus deceleration of YbOH, which can be used to decelerate species capable of scattering only 10s of photons. Then, we discuss radiative slowing and magneto- optical trapping of SrOH, techniques only extendable to species capable of scattering ∼ 104 photons. The last work focuses on spectroscopy of nonlinear molecules to assess the viability of extending techniques of motional control to more complex species. We find a dependence of both rotational and vibrational control on symmetry group, and identify a next-generation candidate for laser cooling. We end with a overview tying these projects together, and assessing the future of motional control along mass and complexity axes, including brief suggestions of how complementary methods to those studied here can further expand into the frontiers of molecular control.