By using Ribbion workbench we can add Buttons and also using outofthebox future command bar editor you can create buttons..You can add this in form, Home, Subgrid.
- 1.Ribbion Workbench
- 2.command Bar Editor
This are the types of buttons in ribbion workbench

Instructions:
- Download ribbion workbench solution
- Install into CRM
- Prepare a new solution only with required entity(include only entity metadata and do not include subcomponents/all assets)
- Add the button into required section
- Prepare the command and attach command to button
Display Rules: Server side
Enable rules(Client Side)