Shakurel Lion has low health and attack power, along with low range and a somewhat slow attack rate. Ability-wise, he strengthens by 100% when he is below 50% HP.
This enemy isn't threatening. Any Normal Cats will make short work of him, as well as strong area attackers such as Paris Cat or Drama Cats. Do not worry about his strengthen, since his base attack power is low enough that it barely makes a difference.