What checks would the federalist have placed on the president to prevent tyranny?

Federalism prevents tyranny because it separates the power so it's not all in one place. This shows separation of power because the government and the states have their own laws/rules which they can enforce as they please. One federal power is the power to declare war.

depends on the age of the teen, many believe by the age of 16 a person should know the strong difference between right and wrong along with the difference between risky and immediate death. swimming with sharks might be dangerous but swimming with sharks while bloody meat is attached to you is just insane. even more if you have no idea what you're doing. however, no matter the age, as long as the person is skilled enough and has the mental and physical capacity to control their actions doing whatever sport they put their mind to is all that matters.