Sample API.AI intent export in JSON format that recognises an emoji entity (sample created in another gist). On importing this intent into another agent, you would be able to roughly detect emojis in user's text.

general.emoji.json

{
  "templates": [
    "@emoji:emoji ",
    "@emoji:emoji ",
    "@emoji:emoji ",
    "@emoji:emoji ",
    "@emoji:emoji ",
    " @emoji:emoji ",
    "@emoji:emoji ",
    "@emoji:emoji ",
    "@emoji:emoji ",
    "@emoji:emoji "
  ],
  "userSays": [
    {
      "id": "252d07ca-7ff6-4df4-a726-355a0552ea51",
      "data": [
        {
          "text": "☺",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 1
    },
    {
      "id": "78310abe-aa85-4a82-870b-2a24f51f4ac6",
      "data": [
        {
          "text": "👍",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "981b08e4-d043-4f86-9378-9d98cd171b8a",
      "data": [
        {
          "text": ":smirk:",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "de0965f3-5b98-4d8d-8abc-bfb31772a95d",
      "data": [
        {
          "text": "😊",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "45b0f3a0-45bd-489e-ab45-fa2fbc5b63cd",
      "data": [
        {
          "text": "😃",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "7debe3c5-d9e3-4121-9e68-99aaf3d4cbf9",
      "data": [
        {
          "text": " "
        },
        {
          "text": "😅",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "4b680982-3e79-47ca-9205-2669085a7de0",
      "data": [
        {
          "text": "(y)",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "7bc35f76-2284-41f6-a232-2e9bf481b0c0",
      "data": [
        {
          "text": ":/",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "9f5c77a1-47f8-48f2-9b1b-9fe90f99cf24",
      "data": [
        {
          "text": ":D",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    },
    {
      "id": "161db599-732a-4b45-8cd6-983794a39534",
      "data": [
        {
          "text": "😉",
          "alias": "emoji",
          "meta": "@emoji",
          "userDefined": true
        }
      ],
      "isTemplate": false,
      "count": 0
    }
  ],
  "id": "9358d1df-854f-48a6-abb4-9112fe672aff",
  "name": "general.emoji",
  "auto": true,
  "contexts": [],
  "responses": [
    {
      "resetContexts": false,
      "action": "general.emoji",
      "affectedContexts": [],
      "parameters": [
        {
          "dataType": "@emoji",
          "name": "emoji",
          "value": "$emoji",
          "isList": false
        }
      ],
      "messages": [
        {
          "type": 0,
          "speech": []
        }
      ],
      "defaultResponsePlatforms": {}
    }
  ],
  "priority": 500000,
  "cortanaCommand": {
    "navigateOrService": "NAVIGATE",
    "target": ""
  },
  "webhookUsed": false,
  "webhookForSlotFilling": false,
  "fallbackIntent": false,
  "events": []
}