There are several games in the running for my most played ever, but honestly I think Fire Red might be it right there. I've put over a hundred hours into it countless times in months-long marathon sessions so many times over the years. Pokemon Red was my first Pokemon game and my first team was the only one I ever got to level 100 cause every game since I keep restarting. Loved that game to death but Fire Red has running shoes and so many other features that it wins hands down even over nostalgia, and Fire Red has mad nostalgia going at this point anyway.
Favored team:
Arcanine (my ****in' boi right thur),
Dragonite,
Scyther,
Kadabra (no one to trade with, for Scyther as well
),
Lapras (I think, it's been awhile), and
Tyranitar.
Current team cause I've been playing again:
Blastoise,
Primeape,
Nidorina,
Raichu,
Pidgeot, and
Arcanine, I've been using a team made almost entirely of Pokemon I could catch before fighting Brock. I had a Beedrill but Beedrill proved too garbage to be worth the frustration and I didn't really want a Butterfree so I went with a five Pokemon team for a while. Then I was just like, "**** it I want an Arcanine".
I also have a "team" of five Meowths I use for training along with whatever Pokemon I'm trying to level up. Meowth has the Pickup ability that gives it a 10% chance to pick up an item whenever you win a battle, and that includes berries, nuggets, and PP Ups, so while grinding for levels I also grind for items. Realizing I could do that was an amazing moment. BTW I have 1 level 14 named "Lieutenant", 1 level 12 named "Sergeant", and 3 named "Private". Because I'm stupid.