Basically you need 2 things: a good processor and good cooling.
As for the processor, a 4th generation or higher i5/i7 is generally the way to go. However, you do not want the
U series. Those are the ultra low voltage which will throttle when under load. Go for an
M,
MQ, or
HQ (ex: i7 4800MQ, i7 4710HQ, i5 4200M). The integrated graphics on these (hd 4600+) are good enough for Dolphin but if you have a dedicated card in the laptop that is good as well. The 4600 (from experience) can do up to 2.5x IR.
The cooling is important as well. Many laptops struggle because they overheat and throttle the processor. Also, most multimedia laptops share the CPU and GPU heatsink which can cause easier overheating if you have a dedicated card in the system. Macbooks tend to have poor heat dispersion. I personally like
Sager Laptops because they have good specs suited for Dolphin (you can get one with just the i7 4710MQ or one with that plus a dedicated card if you do other gaming. Also, they allow you to upgrade the heatsink to prevent overheating.
The laptop I currently own however is an HP Envy with an i7 4700MQ/no dedicated card/8GB RAM and it runs melee pretty damn well. Hope this helped you.
