The bucks are only seen once in the film. They are seen doing their annual run out in the meadow. Two of the bucks are seen using their antlers in a fight for one of the does out on the meadow (Faline's mother and Bambi's mother both already have mates). The bucks stop when the Great Prince of the Forest walks out on the meadow. The last time you see them is when Man is trying to hunt them after their run when they're eating.
The bucks are only seen using their antlers to fight and then when doing their annual run, joined by Bambi, Ronno and the Great Prince.
In the first film, the bucks had two-pointed antlers, whilst in the second film, they had three-pointed ones. This was presumably because their appearance in the second film takes place a few months after their appearance in the first film.
The young bucks in Bambi
The Young Bucks fleeing to escape Man
The Young Bucks first appearance in Bambi II
The Young Bucks second and last appearance in Bambi II