Could you point me to the template definition? I will test it. However, I would be surprised if it works.
I described it by the name I used:
Template:Fast_del.
The markup you used is not well-formed:
<includeonly>noinclude>{{speedydelete|{{{1}}}|{{{2}}}}}</noinclude</includeonly><noinclude>
Alternative "speedydelete" template -- test version:
call it as
<nowiki> <{{subst:fast del|reason|~~~~}}>
</nowiki>
</noinclude>
You probably meant:
<includeonly><noinclude>{{speedydelete|{{{1}}}|{{{2}}}}}</noinclude></includeonly><noinclude>
Alternative "speedydelete" template -- test version:
call it as
<nowiki> <{{subst:fast del|reason|~~~~}}>
</nowiki>
</noinclude>
I tried this (actually just <includeonly><noinclude> stuff </noinclude></includeonly>) previously.
Processing the template markup you wrote with the ExpandTemplates special page on WP (using no parameters) yields:
Alternative "speedydelete" template -- test version:
call it as
<nowiki> <{{subst:fast del|reason|~~~~}}>
</nowiki>
The problem is the parser doesn't pass through the <noinclude> stuff </noinclude> to the page that calls the template. It evaluates it before the page calling the template is rendered. So, the result is <includeonly></includeonly> ... The text <noinclude> stuff </noinclude> is not transcluded at all.
If you like, you can play around with alternative template definitions using the ExpandTemplates special page on WP. Just go to:
http://en.wikipedia.org/wiki/Special:ExpandTemplatesand paste the template definition text into Input Text box.