The list you're looking for can be found linked here. In the list, the Pokemon are split up based on what is unofficially called its "growth rate" or "levelling rate", which you can learn more about here.
The group that reaches level 100 the fastest is called the Erratic group. The Pokemon in it require only 600,000 experience points to reach level 100. However, there are two caveats. The first is that the Erratic group requires the most experience at low levels, but levels off at higher levels to become the fastest to reach level 100 overall. If you are training low-level Pokemon, then the fastest group is Fluctuating (which steepens at higher levels to become the slowest group to reach level 100 overall).
The second caveat is that the Erratic group contains only 22 Pokemon (of which 13 are fully-evolved). Those are:
Nincada, Ninjask, Shedinja, Volbeat, Swablu, Altaria, Zangoose, Lileep, Cradily, Anorith, Armaldo, Feebas, Milotic, Clamperl, Huntail, Gorebyss, Cranidos, Rampardos, Shieldon, Bastiodon, Finneon, Lumineon
This group of Pokemon offers very little variety, and as a result, making a well-balanced team with it would be impossible. If you would like to expand the variety of Pokemon you can use, you could also include some Pokemon from the Fast group in your team (which require 800,000 experience points to reach level 100). The Fast group is consistently easy to level up at all levels, and is outright fastest around level 40 to 70.
