The default view engine in Sails is EJS.
To use a different view engine, you should use npm to install it in your project, then set sails.config.views.engine in config/views.js.
For example, to switch to jade, run npm install jade --save-dev, then set engine: 'jade' in config/views.js.
For instructions on adding support for a view engine not listed above, check out the consolidate project repository.