Cloudwatch Dashboards

You can yes, use a Metric Explorer widget - you'll find Metric Explorer on Explorer option under Metrics in CloudWatch Console.

Dashboard widget definition would be something like:

{
    "type": "explorer",
    "properties": {
        "metrics": [
            {
                "metricName": "CPUUtilization",
                "resourceType": "AWS::EC2::Instance",
                "stat": "Average"
            }
        ],
        "labels": [
            {
                "key": "aws:autoscaling:groupName",
                "value": "my-asg-name"
            }
        ],
        "period": 300,
        "region": "us-east-1",
        "title": "Live instances in 'my-asg-name'"
    }
}