I'd suggest adding your namespaces to your Web.Config
file rather than using a custom template if all you need are using
statements.
<namespaces>
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Routing" />
<add namespace="StackExchange.Profiling"/>
<add namespace="MyProject.mainClasses"/>
<add namespace="Some.Other.Namespace"/>
<add namespace="One.More.Namespace"/>
</namespaces>
This will make those namespaces available in all of your pages without referencing them explicitly.