What do the two Pokemon above have in common?

[Wispy Willow]

They're both incredubly tanky Ghost types (well, when Phantump evolves it becomes tanky but that's besides the point).

Dragonite

 

[GeekyGamerZack]

They both have entries in the Mountain Kalos Pokédex.

Miltank

 

[Max1996]

Both are from the first 2 generations.

Ambipom.

 

[Pika_pika42]

Both are Normal Type Pokemon.

Primeape

~ Pika Pika

 

[NMLewis]

They're both monkey based.

Jirachi

 

[Rainami]

have similar speed and attack

golurk

 

[Wispy Willow]

Both can utalise one hax-reliant strategy or other - Serene Grace Iron Heads for Jirachi and No Guard Dynamic Punches for Golurk.

Lugia

 

[NMLewis]

Both can learn Fly, Golurk being a quite bizarre (and cool) case.

Wimpod

 

[Rainami]

both have abilities that depend on their remaining HP

vikavolt

 

[Max1996]

Both are part Bug-type.

Greninja.

 

[NMLewis]

Both are final stage Pokemon with dual typings.

Shelmet.

 

[Wispy Willow]

Both of them like to be ninjas. Even if one of them has to evolve to realise its true potential.

Roserade

 

[Max1996]

Both are weak to Fire.

Emolga.

 

[NMLewis]

Both have the means to paralyse you.

Relicanth.

 

[Pika_pika42]

Both are not known to evolve from or to any Pokemon.

Kabutops

~ Pika Pika

 

[NMLewis]

Both are Rock and Water type.

Servine.

 

[Max1996]

Both are Rock/Water-type.

Karrablast.

 

[NMLewis]

Both are Gen 5 Pokemon.

Qwilfish.

 

[ocelotlrama jaguar]

Both resist Fighting-type moves.

Dewott

 

[MegaPod]

They're both Water types.

Sudowoodo