This is Speed's form when he got possessed and linked up with the E.V. System, aka temporary evolution. Before that, he used to have a long history with Frost Glaceon until eventually he passed and reborn through Speed. According to PKM, he is a bit quick to temper. And indeed yet, he is really quite aggressive...

For me, I think he should have at least ALMOST THE EXACT same voice to Speed that way there could be some similarities, since the dialogue would be synced up together once they fused.