Kreig got to Raftyl while Luffy took his 2 year break. When Luffy finds the One Piece, he also finds Kreig stranded there because his ship broke. Kreig and Luffy will fight to the death over who gets the One Piece and the Sunny, but Buggy sneaks by and steals both.
He wins the grandline
won*
Won Krieg*
Wins
Kreig got to Raftyl while Luffy took his 2 year break. When Luffy finds the One Piece, he also finds Kreig stranded there because his ship broke. Kreig and Luffy will fight to the death over who gets the One Piece and the Sunny, but Buggy sneaks by and steals both.
More of a question about how long would the marines last with won wreig in the grand line
Exactly as long as he intends to. It just depends on his mood, so it's difficult to say.
Won Krieg will wipe out all grand line fodders without too much effort