IMO any form of speed issues Mudkip may have is easily solved by dumping Quick Claw onto him. Water Pokemon are good ingame because at the very least, great HM slavery usage.
Sceptile... idk. Sceptile was kind of frustrating surprisingly during E4 because for some reason everything carries Ice Beam so it's not really as good as you think it is. Milotic may occasionally survive and KO back with IB, which is annoying. >.<