Rather let's have different colored shinies. We could even have art contestes and the best liked one could go in game.

Cubone, baby Kangaskhan, and M'

When a mother Kangaskhan dies, it leaves its Kangaskhan cub on its own. The Kangaskhan cub uses the skull and a bone from its mother to use as protection and becomes a Cubone. Then through malnutrition or adapting to a different lifestyle, the Cubone evolves into a Marowak. Female Marowak's later evolve into Kangaskhans, and the cycle starts all over.
This is self evident, as Cubone appears rather similar to the baby Kangaskhan that rides around in it's mother's pouch. Also, 'Bonemerang' (Cubone's signature move) refers to boomerang just as 'Kangaskhan' refers to Kangaroo. Kangaroo and boomerangs are both natively Australian themes.
Before Pokemon Red/Blue released, the developers decided that Kangaskhan needed to be separated from the previous two stages to become its own standalone Pokemon. The reason for this is that, being a kids game, it wouldn't do to allow small children to learn that a Cubone is actually an orphaned baby Kangaskhan wearing it's dead mother's skull on it's head and slinging it's bones around like clubs and boomerangs. However, the team didn't have time to delete the code at the last minute. Instead of deleting the code, they simply wrote a new non-evolving Marowak and moved the old one to an empty slot... with no number. This catchable Pokemon is M', Missingno's sister.
M' is actually a scrapped prototype of Marowak. This theory can be confirmed if you catch a M' and level it up, it evolves into a Kangaskhan.

I'm gonna be a downer and say
you can make a charmander from the same sprite
marowak > khangaskhan.... no
the numbers of the pokemon don't correlate

:O I pick Treeko!

I take back what I said about liking only 4 of them  . All ghost pokemon are awesome in their own way.

But after being shown the light by Roloc and Chad29, I'm going back to the ghost pokemon. Srry, guys.
I'm changing my mind after changing my mind about ghost pokemon. I don't know what came over me. Oh yea, it was experience the PO using only one type for the first time. But I see my error. srry ghost pokemon!

so... they're a black market whose captain knows an even blacker market?

ahahahahahaha that's so awesome

so epic...
now we just need one for pokemon..

I guess you could borrow one of your partner's pokemon which is kinda like the battle towers? where you use pokemon which are not yours(but not so much). There could be a feature I guess where pokemon eventually recover hp provided you feed them and give them basic medical aid. I mean pokemon have to eat so it makes sense. If you're talking about paying to have your pokemon revived though, I like the idea of paying for some rangers or another to bring you safely back to the center(with the use of teleport, dig, fly pokemon) safely, so you can heal, better. Anyhoo, I'm just making stuff up.