Character-wise, at least in Tag Force 1, he seems to miss the point of Dueling and thinks it's all about physical strength.
Tag Force 2
In Yu-Gi-Oh! GX Tag Force 2, he has supposedly got larger muscles, but his sprite and model remains the same. Sometimes, there might be a 'random event' where you meet him at the Red Dorm and he will ask for 20,000 DP in exchange for some rare cards.
The player is able to give Alvaro sandwiches. The following tables detail how much he likes or dislikes the sandwiches.