How to show data of user that flagged a content(5 flag types or more)?
As per the "alternatives welcome also" in your question, I would format/present the data in your table in a different format/layout. which will make the data shown in it way more easy to digest/understand.

Have a look at this alternative, which shows the same data (to which I added a few more similar sample rows to illustrate what I mean):

---------------------------------------------------------------------
| User   | Email       | Flag A | Flag B | Flag C | Flag D | Flag E |
---------------------------------------------------------------------
| John   | John@a.com  | 4333   |        |        |        |        |
---------------------------------------------------------------------
| Jack   | Jack@b.com  | 9000   |        |        | 1390   | 7677   |
---------------------------------------------------------------------
| Hamed  | Hamed@c.com | 0123   | 0456   | 0789   |        |        |
---------------------------------------------------------------------
| Niall  | Niall@d.com |        | 3377   |        | 5566   |        |
---------------------------------------------------------------------


If you agree, note however that creating such table is not obvious if you're trying to do so with the Views module. However, using the Forena module (disclosure: I'm a co-maintainer), creating such table is straight forward: it's what is called a Crosstab table. This is a table with a special layout. It is formatted as a grid, with:


the rows representing one or more (combinations of) facts, such as countries or regions, names of persons (or users) like employees / salespeople (or user IDs / user names), names of Models, etc.
the columns representing one or more other facts, such as periods (months of a year, years, etc), available types/flavors of something (like types of errors), etc.
the intersections of rows and columns containing the actual information (data), such as summarized information (counts of something), timestamps, etc. and which might (optionally) include a hyperlink to a drill-down report.


For more info on this, have a look at the "Northwind database" demo videos, i.e:


How to create a report/graph about Shipping summary (fast forward to about 4:15 if you're not interested in the SQL query prototyping part of it).
How to create Crosstab Tables and (related) charts (fast forward to about 2:15 if you're not interested in the SQL query prototyping part of it).


To create such table for each "content page" (as in your question), you can use an appropriate Report parameter, which is like the equivalent of a Contextual filter. In your case, the node's id (= nid) would probably be a good candidate for such parameter. Have a look at this example report, and note the query string (= state=OH) in its URL. Just change that string to, eg,state=IL (or select some other value for state in the Parameters form) to get the basic idea about such parameter. Refer to the tutorial about Forena report parameters for more details about this topic.

This technique can also be applied to any of your entities you want to create reports about (nodes, users, whatever). For example, after you enabled Forena in your own site, you'll have access to one of its sample reports (= Active users), located at /reports/drupaladmin.active_users. If you then follow the link "logs" in that report for any of the users in the report (say with user name = SomeUserName), you'll get the (log) details about that user, via an URL similar to /reports/drupaladmin.user_logs?name=SomeUserName. So in this case the user name is used as such report parameter also.