Ever since BW I feel like all the games became easier and easier, so I have to agree with him. The only challenge I ever felt since then was seriously only some SM NPC's in Poni, Necrozma in USUM and Ghetsis. There are some "challenging gyms in BW", but Gen 3 and 4 gyms and more Gen 2 gyms were all as much or more difficult.
I find gen 1 and 2 have fairly easy gyms with Whitney being the only exception...though nowadays I don't even really have an issue with her.
LGPE was stupidly easy until I got to the end game then it gets much harder.