They shoulda used Mighty in place of Shadow and Fang in place of Blaze. Daisy and Waluigi could've easily been replaced by Toad and a Koopa Troopa.
As much as I hate to admit it, Mighty and Fang are no longer canonical and therefore won't be appearing any time soon. It would be a foolish decision not to put Shadow in, though, as he is the 2nd most popular character behind Sonic, and Blaze is probably not unpopular as well. Still, Daisy as a Speed type seems like a strange decision, as does Vector's appearance in the game at all.
Still, Vector's appearance shows that the Chaotix are growing in their roles as playables, which imo is good to see.