It looks like you can do strike-through with your text by using HTML.
Here is an example:
<p>This text is <del>scratched</del> out!</p>

<ol>
<li>Clean my room</li>
<li><del>Cook Dinner</del></li>
<li><del>Wash Dishes</del></li>
</ol>

You will need to use the embed widget icon (a picture of a TV), and
select Other HTML in order to use strikethrough. This page lists the
above example and displays what it will look like on your page:
https://illnessesanimalsplants.wikispaces.com/Strikethrough

We are looking into improving tables in the future, for the time being
you can use an online site like Google Docs to create your table and
then embed it on your page to ensure formatting.