Is this position legal?

I think I have figured out one method! It takes 13 moves.

No. It's illegal. Black cannot have made the last move in the position shown, but position #4 in post #1 specifies White to play. 

To finish up with Black to play and the same board layout you need only ensure that of the four captures an odd number  occur on light squares, remembering the last capture must be on the back rank (and of course avoiding checks). 

Here's another possibility:

I think the pawns would need to take 8 pieces each side and the only have 7 to take, so illegal.

#2279 is totally legal. Feel free to find a shorter solution.

I stand corrected. It's 8 pieces all told not each side.

Doubt if there is anything much shorter. You could shave a couple of moves off the clean up once the pawns have crossed:

Or, with planning, do the clean up at the start. I'll look at it.

RewanDemontay is getting better at the proof game stuff all the time! Won't take long before I can't beat him anymore

Note: The above pieces are on the opposite side.

And that one definitely is illegal. The pawns can't all promote without any of them changing files, so you can't keep all the pieces.

If it is it shouldn't be.

Is the h2 rook meant to be there or not? It's still appearing in your post.

OK. I just wondered because you hadn't edited it out.

Or faster

Or even more faster. The Black queen only needs three moves to reach it’s destination.

As Arisktotle mentioned earlier.

I didn't think the Black queen was a particular difficulty. I only moved it twice.

Nice puzzle though.

Since when? I don’t see that.

Post #2285. It was a comment on your economical solutions.

I thought you meant @Arisktotle said something about how the black queen moves. I already saw #2285,

Also, while it is true that the Black queen can reach h1 in just two moves, it won’t work, timewise, because of how many units use the a8-h1 diaganol.

funny...