Teddiursa first appeared when Lexi was on Route 5, when he appeared before her. She found out that Team Plasma was trying to capture the Pokémon, and so, confronted them in a battle. Teddiursa got involved in the battle, battling on behalf of Lexi at one point. After this, he joined her team full-time.
Teddiursa preferred not to battle, and so, rarely battled and was more comfortable to observe and watch. He was however, used in the Unova League against Grimsley in B2W2-051.
Teddiursa is a very shy and gentle Pokémon, however, he has shown a great courageous streak within him which leads him to be stronger. Teddiursa is a very social Pokémon who loves to be involved with others, even if he's not primarily the focus.
Teddiursa, being so young, has not yet shown any particular skills.