LogFAQs > #985473643

So from what I can tell, generations are mostly defined by the graphical prowess and grouping similar consoles of similar power together. So 3rd generation is typically 8-bit, 4th generation is 16-bit, 5th generation is 64-bit, etc.

Consoles aren't always released in a neat order, so you get some yearly overlaps. There were 8-bit consoles being released after 16-bit and so forth. I should probably just list the consoles as opposed to this yearly stuff, so I'll do that.

Mobile is where things get weird, because while Game Boy came out around the time of N64 and PS1, it's working on a different set of hardware capabilities altogether. I'll just do a bit of research and add it to where the consensus feels they land in their appropriate generation.