The big thing about top lane is that you've got to have enough sustaining power to handle staying up there for a long time. There are only about 45 AP champions that can handle this: Swain (because his passive returns mana upon killing a creep), Rumble (energy not mana, spell vamp), Kennen (same as Rumble), Vlad (High HP sustain, no Mana or Energy), and Gragas (mana returning ability [although low], built in tankiness, easy ranged creep clearing).
- Swain (because his passive returns mana upon killing a creep)
- Rumble (energy not mana, spell vamp)
- Kennen (same as Rumble)
- Vlad (High HP sustain, no Mana or Energy)
- Gragas (mana returning ability [although low], built in tankiness, easy ranged creep clearing)
The reason you don't see standard AP mid characters in top lane is because A) it is a longer and much more dangerous lane and B) They'll havethey'll end up having mana issues and not sustain well.
As for AD champions, your best bet with those are going to be Corki (heavy ranged harass, good escape. You'll have to build some mana regen stuff though), Caitlyn (highly situational, but possible due to super high range), and Urgot (Very tanky high range).:
- Corki (heavy ranged harass, good escape. You'll have to build some mana regen stuff though)
- Caitlyn (highly situational, but possible due to super high range)
- Urgot (Very tanky high range)
Most common ADs will get pretty abused top, but you can make it work out.
The biggest and most important thing about top lane is the simple fact that from a meta (and mechanical) standpoint pretty much any champion can do it. Top lane isn't so much "Can X champion solo top" as much as "Can X Champion safely lane against Y Champion." So it is really mostly about knowing the match-ups. Just because someone like Malz isn't terribly great top lane doesn't mean you can't make it work, it could just be highly situational.
Hope this helps :)
