Out of the three times i pulled (the gem gacha), i got 1 legendary the first time i attempted that gacha. I would have had a 4th pull but system lagged and i opened a chest instead. The odd arnt good though.
The bucks gacha (15000) doesnt drop any legendaries, but on average i get a blue 2/10.
You can make money by replaying campaign chapters. I have mentioned what you want to do to make chapter 1 grindable, but it takes some patience, and you have to be serious. If you think this free game is a joke, dont play it. Its still in beta form so im hoping playing semi-religiously will put me in a good headstart from others that just started playing today.
ALso, you get a legendary card every 21 days of constant log ins. Im on my 4th one soon.