Is the pokedex planned on how the order is?

Question

The starters are the first Pokemon in each dex, in the order grass, water then fire. Legendaries come last. This didn't occur to me until I noticed, in the national dex, from weaville to frosslass, every single Pokemon is an added evolution to already existing Pokemon. Does the national dex have a specific order for each region?

Answer 1

As you said, starters come first and legendaries come last.
Psuedo legendaries come second last. After the starter's the Pokemon you meet early in the game (eg. wurmple in hoenn, pidove in unova, rattatas in kanto) come in. The Pokemon you face later in the game come before the psuedo legendaries. These Pokemon are usually only encountered after several gym badges are collected. Pokemon only used by the elite 4 also fall in this section (eg. lucario in sinnoh)