I am planning to write a crossover with Metro 2033 and was not sure which pony (Or ponies) I should write for, I was going to write for Fluttershy as I thought it would be interesting to see how she responds to the harshness of life in the metro. However I do not have any concrete ideas on what to write, so everyone say which pony you want to see in the metro and most importantly, why.

I am also looking for someone to proofread/co-author, any one interested must have either played the Metro 2033 game or read the book. Just say below if you're interested.

I've read the book and played the game, but I don't make a great pre-reader or co-author.
You can send me the chapter link before you publish and I can give my thoughts, but I can't help you write it, really.

Any Metro crossover is good in my book. Let's talk about that pre-reading.
As for who to use, I'm actually pre-reading/co-writing(?) a story where the entire mane six end up in the Metro, so you might want to use someone different. Maybe an antagonist that isn't true evil, like Gilda, or Trixie, maybe even Diamond Tiara and Silver Spoon!

Fluttershy would be a good idea and I agree with the guy above me about using an antagonist like gilda trixie and other not truly evil.

As one of my very first stories I tried to do a Metro (mostly game but had elements from the book) crossover with Applejack in Artyom's place, with Braeburn as Hunter and Big Mac as Artyom's stepfather and head of the metro. It didn't take off very well and was quite terrible in my opinion but was still fun to write.
Feel free to PM me any time if you want to if you need help or anything, I'd be happy to help preread or co-write

Although I have never played Metro myself (I actually have it installing at the moment), I've seen a friend of mine go through it, and have actually thought of doing a Metro crossover of my own someday. I'd be more than happy to proofread/co-author, as soon as I go through the game myself, that is. Send a PM if you want my help.