Alakazam is pretty fast, most likely still in the top 10, but after looking over stats Electrode made a severe drop from fastest to 3rd fastest. I think of the available Pokemon in RuSa, Alakazam is third as it sits right now (I think) with a nutural SP score of 339.... here are the top 4 in speed out of ALL Pokemon....based on Nutural Speed scores
Ninjask-1st-419
Deoxys-2nd-399
Electrode-3rd-379
Aerodactyl, Jolteon, and Mewtwo -4th-359
Sure Deoxys isnt available yet, but its speed is second only to Ninjask.... Sorry Electrode. So if Kazam is 339 it is like 7th or 8th overall... not shabby considering out of 386 Pokemon
(edit) I forgot to mention Crobat, also tied for 4th with Aero, Jolt and M2.