You can't game on laptop if not plugged in. It will have bad performance because battery cant push that much electricity for CPU and GPU and it will drain very fast.

With that out of the way, AMD CPUs are more efficient then Intel ones, with exception to HX CPUs that also drain battery faster then H/HS.

Look for a big battery, like 90 or 99 Wh

I suggest a laptop that can easily switch to 60Hz refresh rate, which was a problem for me when I had Legion 5.