use simple BBCode in your comments 
atm follow tags available:
[b]bold[/b] 
[i]italic[/i] 
[u]underline[/u] 
[color=color]text[/color] example [color=FF6600]Text[/color]
list 
[ul] 
[li]number 1[/li] 
[li]number 2[/li] 
[li]number 3[/li] 
[/ul]
[url=http://www.google.com]Google[/url] 
[img=http://uri.to.pic][/img] (fix picsize)
(required wp-syntax) 
[code]your code[/code], 
optional with declaration of the language 
[code lang=”csharp”]your sample code[/code] (all available languages from wp-syntax possible)
<h3>Arbitrary section</h3>
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BBComments

Alex Mills

Implements <a href="http://en.wikipedia.org/wiki/BBCode" rel="nofollow ugc">BBCode</a> in posts.
Examples:
<pre><code>Bold: [b]bold[/b]

Italics: [i]italics[/i]

Underline: [u]underline[/u]

URL: [url]https://wordpress.org/[/url] [url="https://wordpress.org/"]WordPress[/url]

Image: [img]https://s.w.org/style/images/codeispoetry.png[/img]

Quote:

[quote]Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.[/quote]

Bold Italics: [b][i]Test text[/i][/b]
</code></pre>

BBComments vs BBCode