Another thing you could do is make a resource pack and edit the model and look of the mob you are using for your sidekick. Load the resource pack before you load your sidekick mod. To do this, press "Esc" on your keyboard, go into "Options" and click "Resource Packs" You should see your resource pack in there. Bring your cursor over the pack and a play button will appear over the pack. Click the play button to load your resource pack.
If you don't know how to make a resource pack, click here.