They can do everything line infantry can but better and have a high enough morale for prolonged engagements. The premiere assault-troops of the Australian and New Zealand Army Corps, Commandos '90, are incredibly flexible and efficient. Isn't it odd that Ozzies and Kiwi's seem to only get along when there's global conflict? While not the greatest IFVs offensively, they are decently armored, and the 30mm cannon provides serviceable fire-support against infantry and light- vehicles.
Wargame: Red Dragon has dozens of different types, and it can be overwhelming to filter through the options. Humble but numerous, the infantry takes and hold objectives too delicate or too claustrophobic for vehicles or planes to manage.
Infantry is the backbone of any armed force on the planet. "It always comes down to the infantryman and his rifle!" - NATO proverb