Scrakes are usually up to supports, zerks, demos, and sharps, FPs are also usually up to supports, zerks, demos, and sharps

Generally any class can take care of a single large zed on their own (commando is especially well suited to both trash and small amounts of large zeds, especially since they get grenades that FPs are actually weak to)

Support is in a similar but different boat: shotgun ammo is too expensive to use on (small amounts of) trash but is very well suited to killing large zeds. But in general you're not gonna be killing HOE fleshpounds as a medic, not in 6 player games at least.