unfortunately there is no GBA game that has the sinnoh pokemon except for DarkCry a firered hack But I think it only has the Sinnnoh pokemon not sure though.
You could always download AdvanceMap and Put all them in whatever rom you are currently playing.
hey hii i am new to this community can u help me find a gud GBA pokemon rom which has pokemon from all the generations.?? i play these games on a GBA emulator.