What is the theory if black goes 4 Nxc4 in evan's gambit? Ive been learning the theory for this opening but cant find anything if black chooses this line.
You probably mean 4...Nxb4.
White will play 5.c3, and there is probably nothing better than 5...Nc6; so it boils down to being the same as 4...Bxb4 5.c3 Bc5.
[FEN &quot;&quot;]

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.b4 Nxb4 5.c3 Nc6