A Heavy Robot is one of the three different robot classes (the others being Light Robots and Medium Robots) currently available in War Robots. As of the latest version, there are 7 heavy robots. They are the Leo, Fury, Natasha, Griffin, Rhino, Raijin and Lancelot. Since most heavy robots start at level 6 they will automatically be placed within the silver tier. (Rhino starts at lvl 1)
Heavy robots are generally quite slow compared to their medium or light counterparts but compensate with their greater survivability and firepower. They can perform a variety of roles including long-range fire support or close-range brawling depending on their mobility and durability. Heavy robots are much larger than light and medium robots. Most heavy robots (excluding the Griffin and Rhino) have a heavy hardpoint.
Heavy Robots can be specialized for long-range fire support or devastating firepower up close.
The general rule of thumb is that the slower heavy robots (e.g. Fury and Natasha) should be equipped with long-range guns (e.g. 448mm) or artillery (e.g. Zenit). Due to their terrible mobility, they can compensate with long-range firepower, which, combined with their heavy armor, allows them to survive for long periods of time without having to move long distances. However, this can work the other way. Because of their large pool of hitpoints and numerous heavy hardpoints, some Furies or Natashas are armed with multiple Thunders which can be used as semi-mobile beacon defending bunkers. Most robots will not be able to survive the combined firepower of 2 or 3 Thunders.
However, some of the more mobile heavy robots (e.g. Leo, Griffin, Rhino) can perform a variety of roles. These robots, due to their staying power and relative mobility, are oftentimes relegated to breakthrough assault roles (especially the Griffin and Rhino thanks to their abilities). With the right load out, these robots can be absolutely devastating at close range. The Griffin and Rhino specifically have the hitpoints to take hits and tank, while their abilities (jump and assault mode respectively) give them the speed they need to quickly reach and objective, seize it, and hold it. Combined with their firepower, they make effective assault units.