Hello Marshall, a lot was said about Diego Costa, so I decided to take a closer look at his stats.
So first of all, he needs at least 14 Left foot (he scored 11 goals with left foot last season).
Secondly, he is 188 cm tall and his weight is 81 kg.
I would give him slightly lighter skin tone (12). he has not so dark skin IRL.
Lower his AMC to 16 and AMR to 14.
And now for the stats:
Ambition 18 (he is very ambitious), Pace 16, Agility 13, Strength 17, Decisions 17, Flair 14, Finishing 17 (yes 17, because finishing is not so important whiteout composure and he has quite low composure but high finishing IRL too), Long Shots 14, Heading 14, Crossing 12, Technique 16, Consistency 17. I agree with adding him "Shoots with power" PPM, but not with "Places shots" because they are really incompatible together. Also increase his CA very slightly to 168 and give him 175 PA (not because of his recent matches, but because people forget, that he is still very young (25) and has a lot of time to get better and also has an undeniable will to achieve that).
(Note, that this is not an upgrade, there are some downgrade stats suggestions too).