40K space marine assault squads

Assault marines have:
Power armour, bolt pistol, chainsword, frag and krak grenades and a jump pack as standard.
up to 2 marines can replace bolt pistol with a flamer or plasma pistol.
upgrade sergeant to veteran sergeant
both types of sergeants can upgrade bolt pistol to grav or plasma pistol.
both types of sergeants can have melta bombs and/or combat shield
both types of sergeants can have a melee weapon for the space marine armoury:
a model can replace bolt pistol and or close combat weapon for, power weapon, lightening claw, powerfist or thunder hammer.

so in short you can have 2!