The Totodile line is my favorite of Gen 2, I solo'd the main game with just my starter back when I thought that that was what you were supposed to do. That was also the start of my love of the water type. Though, I wonder, if I had known better, could I have solo'd the postgame? I thought the end of the game was the E4 and there was no postgame because most of my games back then didn't have a postgame and I could never beat Giovanni's gym with just my Pikachu. Crustle and Swoobat also bring good memories though I'll never use them in another serious playthrough, saved me in my first playthrough of B2W2 when I was almost defeated in the mandated PWC, naturally I rewarded them by keeping them around and they did pretty well.
Also, Zoroark, I heard about how tough Ultra Necrozma was and my team wasn't exactly well trained back then so I knew it'd be an impossible struggle. My original plan was to have Mimikyu use toxic and just try to survive until it fainted. Well, as expected, Mimikyu fainted, I sent out Zoroark next to do some chip damage and, not even at half health, Zoroark knocks Necrozma out in one hit. Now in my playthroughs of USUM I just start with Zoroark.