Scratch

I don't really know what do you mean by "eat things" (if it's literally eating food and the food is another sprite, you can use the "touching []" block with an "if" inside a "forever").

What I find really annoying (no offense) about questions like this is that they're too vague - in this case there are countless ways in which your sprites would fight, such as like in Pokemon, or like in most action games. You could try explaining how do you want them to fight or maybe comparing it to another videogame or Scratch project.

Welcome to the forums. One thing you can do is make the sprite move toward the food, then hide the food. (After you can make the sprite have crumbs on its face, if neccesary.)    Hope I helped!