Still Pokemon Red. I'm beginning to regret my choices. The choice to include Blue-exclusives, and trade evolutions, because PKHex makes it so easy to do. The choice to try to keep a selection of various typings caught up in level, so I'd have some decent coverage versus brute forcing.

Having the trio of starters. I think I've grown to hate Bulbasaur, at this point. Every time I go to drop him into my party, all I can remember is "Not very effective", over and over again. Well into the 20s, still taking 2-3 Vine Whips to take out a level 6 Kakuna.