Legal?
Sure. Why not? Probably never happen in a real game, but it doesn't look impossible.
If it's legal, what where the last few moves?
The b8-Bishop is a promoted pawn that has come via c6; the Black b-pawn has come from c7. The White King came to a8 earlier via the back rank, then ...cxb6, then the Black Bishop comes to a7, then cxb7, then ...dxc6, the Black King comes to c7 and finally b8=B
Legal?
Sure. Why not? Probably never happen in a real game, but it doesn't look impossible.
If it's legal, what where the last few moves?
The b8-Bishop is a promoted pawn that has come via c6; the Black b-pawn has come from c7. The White King came to a8 earlier via the back rank, then ...cxb6, then the Black Bishop comes to a7, then cxb7, then ...dxc6, the Black King comes to c7 and finally b8=B
That's a possible long range plan, but are you sure it actually works?
That works. SOLV'D
Did SOME one rulez in the **** game of sest,oopz, Chest, woops
Do you mean you can put rules TO or @ a b c Chess.Calm down.
Illegal. White's King never could have left e1.
I never would have guessed. 
3 trophies
To whomever remebers that game with 6 pawns on a file for each side, I indenpently found a game for it in 33.5 moves recently, altough the kings are in different positions. It’s still nice though. It is optimal for just the goal if getting sextupled pawns for each side
Also see it here in my question on Puzzling Stack Exchange: https://puzzling.stackexchange.com/questions
Legal?
Sure. Why not? Probably never happen in a real game, but it doesn't look impossible.
If it's legal, what where the last few moves?