data = [
    {
        "id": 1,
        "type": "Color",
        "tag": "Blue"
    },
    {
        "id": 2,
        "type": "Color",
        "tag": "Red"
    },
    {
        "id": 3,
        "type": "Shape",
        "tag": "Square"
    },
]

expected = [
    {
        "type": "Color",
        "tags": [
            {
                "id": 1,
                "tag": "Blue"
            },
            {
                "id": 2,
                "tag": "Red"
            }
        ]
    },
    {
        "type": "Shape",
        "tags": [
            {
                "id": 3,
                "tag": "Square"
            }
        ]
    }
]

from collections import defaultdict
def transform_result(data):
  # Make a dictionary for each type first, since it simplifies things
  type_map = defaultdict(list)
  for entry in data:
    _id, _type, _tag = entry['id'], entry['type'], entry['tag']
    type_map[_type].append({
       'id': _id,
       'tag': _tag,
    })
  # Make the container {type: __, tags: ___}
  ret = []
  for key, value in type_map.items():
     ret.append({
        'type': key,
        'tags': value
     })
  return ret

assert(transform_result(data) == expected)