Samus technically only has one suit, but it's organic and adapts to the upgrades. This makes "all weapons for each suit" difficult to determine because at which point she finds the suit upgrades vary per-game and Metroid is notorious for sequence breaking.
Samus with a full load-out of all weapons has some scary hax in his arsenal. I'm not sure how Buu would respond to Phazon attacks, but I don't believe the others have a defense against that sort of thing.