My starter is almost 99% of the time the highest levelled, worked that way in HG, 1st White playthrough, Crystal & Gold iirc, R/S, LG, etc.
On Pearl however, since I hated the choices of starters (omg I should have gone with Infernape fml) I chose Piplup, and evolved it, and it became useless. My strongest was a level 100 Golduck iirc. And as for my third Black playthrough, my strongest is an Audino. :)