(In reply to comment #0)

I am reporting several critical issues regarding on table, template and
alignment relationship.

Q#1
In Wikipedia it impossible to put any type of tables in templates. Regardless
if you specific their class or not.

Yes it is, see [[Help:Tables]].

Q#2
Also why is it when you tried to write a new template for other people to use,
all Infobox, Sidebear...etc template will be presented with an extra hidden
<br/>.

Because that seems to be the case:
http://en.wikipedia.org/w/index.php?title=Template:Sidebar_with_collapsible_lists&action=edit
(is this thing at the end of it {{end sidebar page}} causing it?)

Is their a reason for this design or just an error? It is very annoying since
all infobox template will be unallowed to be aligned horizontally. If many
people are against this, could you guys then add an extra element for alignment
for div tags or should this be discussed in MediaWiki.

You can use a style="" or a class="" with CSS to accomplish this. This is not a bug in MediaWiki, but an issue with Wikipedia's local templates. Closing as INVALID.