silly to make legendaries weak
We can all agree Suicine is pretty terrible. We in Europe are stuck with this dog for the next month. I will only use free passes on it and other people feel the same way.
This makes Niantic less money. So why oh why do they make this legendary so poor? Makes no sense.
Answers
It's hardly intentional. Base stats are a product of the Pokemon's stats in the main series, and Vaporeon has the best water moveset currently available.
How is Suicune supposed to compete with that? Give it the same moves and it is just a crappy Vaporeon like every other water Pokemon that has Water Gun + Hydro Pump.
I think they at least tried by giving it a niche with Hidden Power, although the annoying thing is not being able to change the Hidden Power type.
Anyway not every Pokemon can be equally viable, with how many Pokemon are in the game, it'd be impossible to make them all as good as each other. Just because it's legendary doesn't make it automatically better or must mean. Blaziken and Greninja are starter Pokemon and are in the same usage tier as legendaries in competitive.