The main advantage holding back from evolution has, is that the moves are learned sooner. Aside from that, there's no difference at all.
Naturally, the sole exception to this is the Stone evolvers, all of which only learn 1 move on their final form. --- Where logic won't work - I will PAL Gamers unite - http://www.gamefaqs.com/boards/277-pal-gaming
Wow, this is pretty funny because I was just about to answer the same question about my Squirtle... It's level 67 and I was afraid it would be hold off from the stats if I kept holding off on the evolution. --- Check profile for contacts.