>>724214750
Your bottleneck for PS2 will be the actual emulators available, Android PS2 emulation sucks because of the lack of work done on it. Dreamcast meanwhile is one running basically flawlessly, anything that's capable of N64 and PSP emulation is probably capable of Dreamcast emulation.
PS2 will probably depend on when in the console's lifespan the game you want to play came out, stuff like Kingdom Hearts from early life will most likely be fine even on the emulators available.