How to make a table editable in a keynote template? When adding Images, Text &amp; Shape to a Master slide you have the option of Define as Media Placeholder.

No such option (appears to) exists if you add a Table to a master slide. This means that when someone adds a slide from a template which contains a table it is non-editable.

Is there anyway of adding a Table to a Master Slide which allows that table to remain editable?
No.

The only thing you can do is to add an object placeholder to the master so that the table gets inserted with the desired position/dimensions.

Plus a table style with the desired color scheme. If you then delete all the default table styles, your custom table style gets applied when inserting the table into the slide.