[Episode 9 crashes constantly.]

When attempting to do most anything after updating I receive the following error:

So far it happens when interacting with HM items (Boulderers/Rock Smash Rocks/Trees), when trying to save, and when interacting with NPC's and event Pokemon (like the Zangoose I'd saved in front of a few days ago), and the newly added signs.

Thus I am now unable to do anything.

EDIT: Forgot to mention, I first just updated from 8 to 9, but I've since removed it and freshly installed and it continues to happen.

EDIT2: Attempting to open the PC I got a different error, though related it seems:

Starting a new game it seems I do not receive the error though.

[Meditite or Medicham location??]

I'm afraid they're not currently obtainable as far as I'm aware. I've yet to find one anywhere and the Obtainable Pokemon list seems to confirm.

[looking for zigzagoon or another headbutting pokemon]

Zigzagoon is obtainable in an alleyway (as an event) in the Obsidia Ward.

Besides that since I'm not sure if it's weather/time related or not (or how far along you are), the two easiest and earliest obtainable to get it with would be Bidoof/Bibarel (who learns it at Level 17/18) and Snubbull (given to you as a gift after you've obtained the first badge in a house in the Peridot Ward - Snubbull learns it at Level 19).

If you're far enough along, Karrablast (as long as it's caught at Level 36 or lower from there) outside Spinel Town would have Headbutt at capture (and as a plus, in my opinion, False Swipe as well).

Hope that helps.

[Misdreavus]

In regard to Bulbasaur, if you go back to the island after completing it you'll find a change there.

For Misdreavus, I put it off after finding it the first couple times (to make sure I could capture it if necessary - which it isn't I'd note it gives itself to you), and it seems it does have to be night. I never saw it when I cleared the rest of the extra stuff (save Mudkip, waiting for the right weather) during the day for easier visibility, though it was located in a place I definitely passed through earlier that day. For me at least it was also visible every time, yes.

[Pokemon Evolution Theories.]

While I never thought of it that way, I do see two issues with thinking they mightn't do anything with older Pokemon because the regions are separate.

The first being they are a business and any good business tries to make their product make as many people as happy as possible. Many want pre/evolutions, so as a business they'd be remiss to not do so (a second time in a row at least).

The second, coming at it from a story and environmental point of view, many animals have been introduced to new areas (intentionally or not) and can and will change the environment, and be changed to suit the environment as natural selection is wont to do. So they can be easily explained as simply, for all intents and purposes, forcing a change to the Pokemon by changing it's environment.

As for me, two on my top ten list (minus babies) would be:

1.) Machoke alternate evo. Obtained by removing the Power Saver belt that locks in it's power. If something looking like Machamp results from his contained power it'd be interesting to see what an unleashed (er... unbelted) form would look like. Though it would probably end up with some sort of draw back like Slaking and Regigigas to rein in it's overall battle power.

2.) An evolution for Starmie (Starus). Not so sure about the how, but it does have that core in it. It's core somehow becoming denser and starting nuclear fusion within it making it a Water/Fire-Type and dropping some speed to gain other stats makes sense to me.

The latter actually makes more sense where I'm taking it from though. In my obsession over the years I've got information for story/Pokemon/"bad guys"/base stats/moves etc. for 3 regions. Starus is actually one of those few in my first region, but to explain how it makes sense would require recapping most of the story and make this post about 2 pages long for the abridged version and since they don't have the capabilities in the real game as in my stories - at the moment at least anyway - explaining it wouldn't even really help.

Regardless, that basis is one I'd love to see, no matter how it came about.

[Poliwag]

Not sure if it's the only place (or if it's weather/time dependant), but I found mine in the grass in the Hidden Cove (during a windy day).

[Ghastly and Eevee]

Not right from the train itself, no but it's further right from the entrance to the area the train is in, yes:

Screenshots pieced together.

[Swinub]

Swinub is farther ahead.

It's a normal wild find in the areas surrounding Spinel Town, which is currently the last place.