Thanks for your reply. I guess we can tell the default-loaded modules via investigating the source of Catalyst.pm like the following :

use Moose;
use Moose::Meta::Class ();
extends 'Catalyst::Component';
use Moose::Util qw/find_meta/;
use B::Hooks::EndOfScope ();
use Catalyst::Exception;
use Catalyst::Exception::Detach;
use Catalyst::Exception::Go;
use Catalyst::Log;
use Catalyst::Request;
use Catalyst::Request::Upload;
use Catalyst::Response;
use Catalyst::Utils;
use Catalyst::Controller;
use Devel::InnerPackage ();
use File::stat;
use Module::Pluggable::Object ();
use Text::SimpleTable ();
use Path::Class::Dir ();
use Path::Class::File ();
use URI ();
use URI::http;
use URI::https;
use Tree::Simple qw/use_weak_refs/;
use Tree::Simple::Visitor::FindByUID;
use Class::C3::Adopt::NEXT;
use List::MoreUtils qw/uniq/;
use attributes;
use utf8;
use Carp qw/croak carp shortmess/;
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