>>> df["rank"] = df.groupby("group_ID")["value"].rank("dense", ascending=False)
>>> df
     group_ID item_ID  value  rank
0  0S00A1HZEy      AB     10     2
1  0S00A1HZEy      AY      4     3
2  0S00A1HZEy      AC     35     1
3  0S03jpFRaS      AY     90     1
4  0S03jpFRaS      A5      3     5
5  0S03jpFRaS      A3     10     2
6  0S03jpFRaS      A2      8     4
7  0S03jpFRaS      A4      9     3
8  0S03jpFRaS      A6      2     6
9  0S03jpFRaS      AX      0     7