What are examples of grandmaster games where both Black and White castle opposite sides and the queenside players loses? I want to become better at attacking my opponent king when they castle queenside. What are Grandmaster games where the players who castles queensides gets mated or loses due to a powerful attack on the queenside?
That's a pretty typical scenario, you'll find a lot of examples if you search for games in the sicilian opening.

[Event "Sarajevo"]
[Site "Sarajevo BIH"]
[Date "2000.05.29"]
[EventDate "2000.05.17"]
[Round "11"]
[Result "0-1"]
[White "Sergei Movsesian"]
[Black "Garry Kasparov"]
[ECO "B90"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "64"]
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be3 e6 7.f3
b5 8.Qd2 Nbd7 9.O-O-O Bb7 10.g4 Nb6 11.Qf2 Nfd7 12.Kb1 Rc8
13.Bd3 Rxc3 14.bxc3 Qc7 15.Ne2 Be7 16.g5 O-O 17.h4 Na4 18.Bc1
Ne5 19.h5 d5 20.Qh2 Bd6 21.Qh3 Nxd3 22.cxd3 b4 23.cxb4 Rc8
24.Ka1 dxe4 25.fxe4 Bxe4 26.g6 Bxh1 27.Qxh1 Bxb4 28.gxf7+ Kf8
29.Qg2 Rb8 30.Bb2 Nxb2 31.Nd4 Nxd1 32.Nxe6+ Kxf7 0-1