Category Template

Woo! I found how to do it, possibly it won’t be the cleanest way, but for others wondering – here is a custom page.php file that I named page-testimonials.php and manipulated the loop:

<?php
/**
 * Template Name: Testimonials (faux category)
 *
 * Learn more: http://codex.wordpress.org/Template_Hierarchy
 *
 * @package WordPress
 * @subpackage Twenty_Thirteen
 * @since Twenty Thirteen 1.0
 */

get_header(); ?>

	<div id="primary" class="content-area">
		<div id="content" class="site-content" role="main">

			<div class="custom-cat">

				<?php if ( have_posts() ) : ?>
					<header class="archive-header">
						<h1 class="archive-title"><?php the_title(); ?></h1><!-- .entry-title -->
					</header><!-- .entry-header -->

					<div class="entry-content">
						<?php /* The loop */ ?>
						<?php
							$args = array( 'post_type' => 'testimonial', 'posts_per_page' => 10 );
							$loop = new WP_Query( $args );

							while ( $loop->have_posts() ) : $loop->the_post();
								echo '<article class="custom-cat-post">';
								echo '<h3 class="custom-cat-title">';
								the_title();
								echo '</h3>';
								echo '<div class="custom-cat-content">';
								the_content();
								echo '</div>';
								echo '</article><!-- .custom-cat-post -->';
							endwhile; ?>

						<?php twentythirteen_paging_nav(); ?>

					<?php else : ?>
						<?php get_template_part( 'content', 'none' ); ?>
					</div><!-- .entry-content -->
				<?php endif; ?>

			</div>

		</div><!-- #content -->
	</div><!-- #primary -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>

Notes:
——
The below is me adding custom containers around the_title() (the post title) and the_content() (the post content), you can remove these or add change them. The same goes for the classes: custom-cat, custom-cat-post, custom-cat-title and custom-cat-content.

echo '<article class="custom-cat-post">';
echo '<h3 class="custom-cat-title">';
the_title();
echo '</h3>';
echo '<div class="custom-cat-content">';
the_content();
echo '</div>';
echo '</article><!-- .custom-cat-post -->';