Just replace you iron-pages:
<iron-pages selected="[[page]]" attr-for-selected="name">
<my-view1 name="view1"></my-view1>
<my-view2 name="view2"></my-view2>
</iron-pages>
With neon-animated-pages and chose your entry and exit animations:
<neon-animated-pages selected="[[page]]" attr-for-selected="name" fallback-selection="404" entry-animation="slide-from-bottom-animation" exit-animation="fade-out-animation">
<my-view1 name="view1"></my-view1>
<my-view2 name="view2"></my-view2>
</neon-animated-pages>
Install neon-animation with bower install --save PolymerElements/neon-animation
Include the elements:
<link rel="import" href="../bower_components/neon-animation/neon-animated-pages.html">
<link rel="import" href="../bower_components/neon-animation/animations/slide-from-bottom-animation.html">
<link rel="import" href="../bower_components/neon-animation/animations/fade-out-animation.html">
And you are good to go.