Odd one out!

[Enpatsu Shakugan]

Squirtle isn't a stage 2 evolution.

Magmar, Magmortar, Magby

 

[Hyzenthlay]

Magmortar gets access to extra moves.

This has more to do with the anime (regarding Ash):
Pidgeot, Noctowl, Honchkrow

 

[PageEmp]

Pidgeot is from a 3 stage line.

Venusaur, Gardevoir, Raichu

 

[Enpatsu Shakugan]

Gardevoir I'm sure is way more prominent jerk off fodder for nerds, haha.

Litten, Arbok, Milotic

 

[Ninetales]

Litten isn't serpentine.

Bellossom, Liepard, Drapion

 

[PageEmp]

Liepard isn't from an even numbered generation

Cofagrigus, Jellicent, Xatu

 

[Hyzenthlay]

I'm gonna say Xatu is the odd one out for not being Ghost-type or from Gen 5!

Aipom, Minccino, Meowth

 

[Arma]

Aipom got its evolution in a different generation then it was released in!


Eevee, Dragalge, Torracat