Evolutionary Lines in each generation

Evolution is a crucial part of Pokémon and with each new generation, several evolutionary lines (two staged or three staged) have been introduced. This post is aimed at calculating the number of evolutionary lines introduced in each generation as well as the number of Pokémon introduced in the same generation without any evolutionary lines.

Note:

• Branched evolution in the same generation are counted as their own separate evolutionary lines. For example, the Eevee line in Generation I (giving three separate two-staged evolutionary lines from 4 Pokémon) as well as the Wurmple line in Generation III (giving two separated three-staged evolutionary line from 5 Pokémon).

• Mega Evolution is not considered.

• Evolutions/pre-evolutions of older generation Pokémon introduced in later generations are counted as single lines, unless they have another evolution/pre-evolution in that same generation. For example, Umbreon and Espeon are counted as separated single staged Pokémon as they do not have a shared pre-evolution that was introduced in the same generation. On the other hand, Budew and Roserade belong to the same evolutionary line but since their middle stage evolution is not of the same generation, they are counted as a two-staged evolutionary line.

• Regional variants are not considered. Newly introduced Pokémon which are evolutions/pre-evolutions of regional variants (e.g. Obstagoon, Mr. Rime, etc.) are considered.

Generation I

Total - 153

• Three branched evolutionary lines were introduced in Generation I, which were the Vaporeon, Jolteon and Flareon lines. Discounting two lines gives the original 151 total number.

• 51.66% of all Generation I Pokémon are part of two-staged evolutionary lines.

Generation II

Total - 100

• No generation exclusive branched evolutionary lines were introduced in Generation II.

• Taking generation exclusivity into account, 44% of all Generation II Pokémon are single-staged, thus forming the majority of this generation.

Generation III

Total - 138

• Two branched evolutionary lines were introduced in Generation III, which were the Wurmple and the Clamperl lines.

• Discounting these two lines plus Shedinja/Ninjask gives the original 135 total number.

• Taking generation exclusivity into account, 42.96% of all Generation III Pokémon are part of two-staged evolutionary lines.

Generation IV

Total - 108

• One branched evolutionary line was introduced in Generation IV which was the Burmy line. Discounting either one gives the original 107 total number.

• Taking generation exclusivity into account, 42.99% of all Generation IV Pokémon are not part of any evolutionary lines.

Generation V

Total - 156

• No generation exclusive branched evolutionary lines were introduced in Generation V.

• Taking generation exclusivity into account, 46.15% of all Generation V Pokémon belong to two-staged evolutionary lines.

Generation VI

Total - 72

• Like Generation II and V, no generation exclusive branched evolutionary lines were introduced in Generation VI.

• Taking generation exclusivity into account, exactly 50% of all Generation VI Pokémon are part of two-staged evolutionary lines.

Generation VII

Total - 90

• One branched evolutionary line was introduced in Generation VII which was the Cosmog line. Discounting either one gives the original 88 total number.

• Taking generation exclusivity into account, 36.36% of all Generation VII Pokémon are part of two-staged evolutionary lines.

Generation VIII*

Total - 81

• One branched evolutionary line was introduced in Generation VIII which was the Applin line. Discounting either one gives the original 80 total number.

• Taking generation exclusivity into account, exactly 41.25% of all Generation VIII Pokémon are part of two-staged evolutionary lines.

Comparison of all Generations-

By total number of single-staged lines introduced (Generation Exclusive)

By total number of two-staged lines introduced (Generation Exclusive)

By total number of three-staged lines introduced (Generation Exclusive)

By percentage of single-staged lines introduced (Generation Exclusive)

By percentage of two-staged lines introduced (Generation Exclusive)

By percentage of three-staged lines introduced (Generation Exclusive)

Final notes

• Generation IV introduced the highest number of single-staged Pokémon without any generation exclusive evolutionary relatives (46). This can be attributed to the addition of numerous pre-evolutions/evolutions of older generation Pokémon as well as non-evolving legendary Pokémon.

• Generation I introduced the highest number of two-staged evolutionary lines with 40 whereas Generation V introduced the highest number of three-staged evolutionary lines with 19. This may be due to the fact that both of these generations introduced the most number of Pokémon with 151 and 156 respectively.

• 83.44% of all Generation I Pokémon are evolutionary relatives with other Pokémon in the same generation, thus making Generation I the generation to introduce the highest percentage of such related Pokémon, but only by a small margin with Generation VI (83.33%) and Generation V (82.69%) close behind.

• Generation I and Generation III introduced the most generation exclusive branched evolutionary lines (3).

• However, in terms of unrelated lines, Generation III has the most with 2.

• Branched evolutionary lines in all generations are two-staged except for the Wurmple line in Generation III and the Cosmog line in Generation VII.

• The Wurmple line branches in the first stage while the Cosmog line branches in the second stage.

• The Wurmple line also has the most number of Pokémon in its evolutionary line with a total of 5. The Cosmog line and the Eevee (Gen I) line come in a close second with 4 each.

*- Gen VIII Pokémon at the time of writing.