If you were to cancel the evolution of Chimchar to Monferno at level 16 and continue with the Pokemon Chimchar until level 41 (Monferno evolves to Infernape at level 36) and then decide to evolve it at level 42 who would it change in to? Monferno or Infernape?
A Pokemon cannot skip evolutions in the game; they can only do that in TCG.
In your example, it'd evolve into a Monferno at L42, and then an Infernape at L43.
It would just evolve to its second stage after one level and then to its third stage after another level let's say you have a lvl 38 Chimchar at level 39 it would evolve in Monferno and at level 40 it would become Infernape.
Just in case previous answers did'nt answer your question