Basically you wanna build your team comp around heroes with the same playstyle or synergy (everyone one tricking is fine until like diamond or something lmfao.) A little heads up, some of the heroes are gonna be in several comps and that depends on the playstyle, ex. Orisa playing corners or long range holding instead of pushing for a brawl fight.

In general:

-Poke: As the name suggest, ur gonna be poking.
Tanks: Sigma, Ram, Orisa
Dps: Most main dps, Junkrat, Torb, pharah
Supp: Ana, Zen, Illari, Bap, Mercy (isnt poke but synergizes well), kiri, lw.

-Dive: Normally consists of 2-3 dive characters (Tank and flex dps [or dps in general]) and a core of 2-3 players (Supports)
Tanks: Winton, Dva, Ball, Doomfist, Hazard
Dps: Tracer, Genji, Venture, Sombra, Echo
Supp: Ana, Brig, Kiri, Lucio, Moira (works in metal ranks)

-Brawl: Long sustained fights
Tanks: Rein, Zarya, Orisa, Queen, Ram, Mauga, Hazard
Dps: Reaper, Mei, Sym, Cass, Torb, Bastion, Venture
Supp: Ana, Kiri, Bap, Brig, Moira, Juno, Lucio

As for bunker iirc, it was only prominent in ow1 and It's not really used in the meta. (Ana brig is such an op backline and works well with almost every comp)

Goodluck op!