In a gaming laptop you are looking at the i7 and nothing else. Generally speaking they have more cores and clock higher anyway.
EDIT: Just checked and it looks like for Skylake Intel now offer core i5 processors with 4 cores (physical) in the mobile space. They are still clocked slower though.
http://ark.intel.com/products/family/88393/6th-Generation-Intel-Core-i5-Processors#@Mobile
http://ark.intel.com/products/family/88392/6th-Generation-Intel-Core-i7-Processors#@Mobile
Ignore anything with a "U" in the name - these are the ULV models.