This piece of shit game is still being xphacked and has been since 2001. All of the high level characters are mostlikely xp hacked as its incredibly easy to do and still has not been fixed. I have ticketed nexon more than once on this issue and they refuse to fix it, so again, I present the XP hack to you.
There are more than five ways to do this, but heres the easiest one.
First, You will need ONE sub and a decent amount of sub xp so you don 't pull up weird values. You will also need CheatEngine (

Once you have your sub XP in your assign sub XP screen, you will need to search the value in CheatEngine.
If you pull up like 20-30 values, add all of them to your CheatEngine address list and change the value to 7350000. This should be done while the assign XP window is open. Afterward, exit the Assign XP window and re-open it. Search for your SUB xp value again and the correct values will be set to the original sub xp and will narrow down your invalid results.
Now, once you find the correct value, set a Hotkey (F2) and the hotkey should set the value to 7350000.
Second, you need to do a text string search for your subordinates name, so if your sub would be SonyStyle then you'd search SonyStyle.. you should only find about 5-10 values and freeze them all to KruSucks(this is important, or you'll have to keep getting sub xp each time)
So, now when you open your assign sub xp screen, you will see your subordinate KruSucks with your original sub xp value. Assign the SUB xp to one of your units, press F2 and you will see the XP value go up to 7350000.
Press OK and VIOLA lvl 60 unit.
Rinse, Repeat. Open SUB xp screen and you will still see KRUSUCKS sub with its original XP value, assign the XP and press F2, then press OK.. VIOLA.. lvl 60 unit.
FUCK KRU!
If you have any other interesting hacks you'd care to share with me, or hack ideas (please, know wtf you're talking about) you can add me to msn


PEACE BITCHES
I stil know 5-6 high lvl chars(60+) who have xphacked their way up there, and are untouched by KRUSUCKS
PS: If you want to use this on Relic, the XP value is 500000 for lvl 25 units.