Requirements can typically be expected to be around or close to the requirements you need to run Pcsx2 decently. Also the Gamecube and Wii are more powerful systems than the PS2, I'm not sure if they are more complex than the PS2.
I know on an AMD Athlon 64 X 2 3800+ Pcsx2 runs about half speed or less than half speed with most 3D games, games on Dolphin such as RE Remake ran anywhere between half and almost full speed, RE4 never went above 6 - 10 FPS on Dolphin.
A Pentium 4 on Pcsx2 would lag like heck, even an AMD64 X 2 is not sufficient enough, I honestly can't imagine a Pentium 4 being able to run anything on Dolphin decently either, unless it's a 2D game or a game with a very minimal amount of 3D geometry.
I know on an AMD Athlon 64 X 2 3800+ Pcsx2 runs about half speed or less than half speed with most 3D games, games on Dolphin such as RE Remake ran anywhere between half and almost full speed, RE4 never went above 6 - 10 FPS on Dolphin.
A Pentium 4 on Pcsx2 would lag like heck, even an AMD64 X 2 is not sufficient enough, I honestly can't imagine a Pentium 4 being able to run anything on Dolphin decently either, unless it's a 2D game or a game with a very minimal amount of 3D geometry.