Dark Legend

In my opinion, best type is BIDOOF

Strength sounds pretty relative to me. This is subjective, but I really like the Dark type because it includes many Pokemon that can turn enemies strength against themselves and many of these Pokemon also know the Prankster ability, which comes in handy more than once when you want to set up strategies regardless of the speed of your foes. Having that said, I would go for Fire types in terms of pure strength, even though most of the Pokemon belonging to this typing can be pretty frail at times, which is why speed can't be neglected if you decide to opt for a Fire Monorun. Objectively, I would say that Dragon Pokemon are probably the most versatile of the game.

Most definitely the Fairy type. On one hand, being only weak to two terrible offensive types (steel and poison) make it a great defensive staple, since you don't really see pokemon running that kinda coverage. On the other hand, resisting heavily offensive-oriented types, like dragon, dark and fighting is very useful, because that means it can switch around a lot and just counter stuff. Fairy is also a fantastic offensive type, thanks to its heavily spammable STAB moves, which are only resisted by 3 types —steel, fire and poison—, an issue that can be alleviated by most of the faries' good coverage