Up and At 'em, Fellas
Pikachu only had one goal in mind. To be just like his hero, the Great Pikachu. This is, of course, the very same Pikachu that belongs to Pokemon trainer Ash, and even the Pokemon on the island were aware of the things he's done long before the events of Poké Island transpired, just by way of news and televised events. And after Poké Island, there wasn't anyone left who didn't know who he was. Of course, not many people were crazy enough to want to be just like him, or even greater than. All except one, this young Pikachu right here.
Pikachu was obsessed with this goal. Once he formed Team Pika with his friends (which no one objected to because they both believed in the idea and were also too lazy to object), life became way way way more difficult for his teammates. On a near daily basis, Pikachu would wake his teammates up bright and early to for Pokemon training. And not just battle training, but survival training, exploration training, and stamina and endurance training as well. And even though they were used to this, the rest of the team never found themselves enjoying it.
As leader, Pikachu would often delegate tasks to individual members of Team Pika, come up with strategies, and then execute those strategies. He is an excellent planner, and is really good at keeping schedules. He also really loves adventure. However, he can be bossy and a bit uptight. And even though he feels what he's doing is what's best for the team, sometimes he gets a little too caught up in his own ambition. His method of achieving that ambition is pretty noble, though, as he and his team go out of their way to help others in need and assist with tasks, much like a very early prototypical rescue team from the Pokemon Mystery Dungeon series long before that series existed. On the downside, however, Pikachu's zealotry often had him signing up the team to take on tasks that were usually more than they could handle, or fighting against Pokemon forces that were clearly more than a match for them.
As the series progressed from Poké Tales to the end of Poké Legends, he mellowed out and became less pushy, forcing his friends less and less to do things they didn't really want to do, as he started to realize that there was more to life than just chasing after an obsession he had. By the end of the series, Pikachu would lead his team to take on tasks because it was the right thing to do, not just to get accolades and have his own personal monument built in his image. It was no longer important to be like the Great Pikachu, because in his mind, he and his team are already pretty great.
Outside of his role as a leader, Pikachu is a kind individual and generally level headed. He's no genius, but he's pretty smart and rather clever, too. He's not very open with strong emotions, such as extreme sadness or feelings of love, but he does have sort of an attraction to Clefairy, even though he's no very good on acting upon it, and shies away from coming forward about it. Even by the series end, Pikachu and Clefairy just kind of know they like each other, but the whole "will-they-won't-they" between the two of them is never really resolved.