Personally, I think that a Lvl. 100 Pokemon should be a reward given for effort as opposed to a trophy made by an outside device, but I can see why some people choose to hack their Pokemon up to high levels. The only thing I have against level hacking is when people hack for max stats(Lvl. 100s with 999 in all stats), as that got annoying during my childhood. As for myself, I have a full team built to Lvl. 100 on my FireRed, and honestly, once you can't train them anymore, things get kinda dull. If you don't have a rival to compete with, the game starts to lose its appeal, and with the rise of new Pokemon generations including upcoming Black/White Version II for the 3DS, 3rd gen rivals are tough to come by. I know I got a little off-topic there for a bit, but it all sorta adds to the point. The method of obtaining Lvl. 100 Pokemon is a personal choice based solely on one's reasoning for having them; be it for use or show.