Chatot maybe?

Chatot Timid (+Speed, -Sp.Attack) 255 Sp.Attack/ 255 Speed (Approx. 140 Sp.Atk, 155 Speed) Salac Berry (+ 50% Speed when below 50% is reached --> 225 Speed)

Heat Wave Chatter Hyper Voice Endure/Substitute (to activate Salac Berry)

The only problem with this Chatot is that he would have to be on a separate team than my Medicham, who will also be using a Salac Berry for the speed boost.