The GBA has A, B, and two shoulder buttons. The only two portable fighting games I played that much of were Gameboy Samurai Shodown and Killer Instinct. Even though they were simplified to allow for fewer buttons, they were kind of fun. But since GBA has two extra buttons, I imagine they could probably make fighters more complex than those, although it may be awkward to use the shoulder buttons. (I almost never used the L button when I played Street Fighter 2 years ago.)

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