Including MEC in your theme means for seamless integration of both, you need to adjust dummy shortcodes. If you’re going to include the Modern Events Calendar in your theme, then please use the following as a guide.
To include the Modern Events Calendar plugin in your theme, you can simply use the TGMPA plugin. It works completely fine with this plugin.
For a better User Experience, MEC imports events and shortcodes upon activation. If you want to disable this feature for any reason, you can use the two following filters:
Disabling Dummy Events,
Disabling Dummy Shortcodes (Not Recommended if you’re not going to add your own shortcodes!).