I Just Shifted Myself.

Interpersonal skills. A good leader needs to be able to read and understand people.

Diplomacy skills. Making peace and compromises both within and outside the group will make life easier.

Problem solving skills. As a leader his people will look up to him for guidance when things go wrong.

Planning and strategy. Especially long term planning, being able to predict what will happen down the line if a certain action is taken.

He should also be trained in his groups history and culture. He should be painfully familiar with his people, more so than the commoner.

Basically he needs the same set of skills to be a leader of this group as any king would ruling a country.

- He'd sit in on meetings, to learn how they're conducted.

- He'd probably also socialise with the other important people in the group, to get to know them.

- His father might start giving him small responsibilities, later on, so he can start earning the other Felines' respect.

- Lessons in diplomacy, within the group and externally. This would include things like how to respect different cultural attitudes. He'd learn about the other groups he has to deal with, and assuming relations are currently good he'd likely be taken to meet some of them, to begin the foundations of the future relationship.

- Language lessons, if he'll have to deal with people who don't speak his language. While leaders usually have specialised translators, it's advantageous if they can speak some of the major foreign languages.

- History lessons, to see the mistakes and good decisions of his predecessors, and the kind of situations leaders find themselves in. His father would also give lessons from his own experience, which'd be even more useful due to chronological immediacy.

- The above might cover military strategy, if that's required. He's not only got to learn how to fight, but how to lead others effectively. There's more complexity to a large-scale fight than just "you, claw some guys".

That's all I can think of for now. Hope it helps!