in terms of typing what I find weird, is how they gave Grass a fairly shitty sense of resistances/weaknesses (frankly half the time it loses to electric because it gets paralyzed and outpaced in damage), and how they just didn't make very many fire Pokemon, let alone strong ones. Outside of starters and legendaries, there are only a handful of options. And then ofc competitively in Gen 3 Dugtrio exists so you're not gonna get anywhere unless it's a fire/flying type, and then they made stealth rock lol.
Then the weirdest is Fairy. Like I don't understand why you design a type, basically make it a better psychic. You make it immune to Dragon because the Dragon typing doesn't have enough weaknesses. I already don't like it, because pre-Gen 6 Dragon's typing made it the perfect boss type for the champion. A lot of your usual offensive strats wouldn't hold up against Dragons, especially against Pokemon with such strong stats. Creating fairy makes it feel less "cool" like it's just another type.
But anyways you wanna nerf dragon so you make fairy. Because the Dragon Pokemon are strong right. So then you also make it strong against Fighting, which another really good type, and Dark, which up to that point was a good Type. Well making it strong against Fighting was Psychic's one strong point atp in Pokemon, so now Psychic's even worse, and being good against Fighting and Dark is an exceptional combination on its own, It's like a better Dark type even without the whole dragon thing.
And then mess with Steel's identity of being a good defensive type so now it's in this weird valley where it has a ton of resistances still but not the best ones (aside from fairy and dragon, electric, ground, fire, water, fighting, Dark, Ghost, are probably the best common offensive types in the game). Which is also screws with Pokemon like Bronzong and Metagross who's whole thing was being Psychic/Steel so that they could be neutral to Dark and Ghost while still having Psychic coverage. At least they threw poison a bone lol