Ok so to unlock blue vegeta and goku you have to beat arcade but I also heard you can unlock them by farming zeni ....
The final way to unlock Super Saiyan Blue Goku and Super Saiyan Blue Vegeta is to simply spend a lot of time playing the game. Dragon Ball FighterZ dishes out Zeni (its in-game currency) as you fight. You can earn Zeni in Story Mode, Arcade Mode, and even Versus Mode. However, it's worth mentioning that tournament fights do not give you Zeni.
Once you reach a certain amount of total Zeni, you'll unlock the Super Saiyan Blue characters. You'll need to earn 300,000 Zeni to unlock Super Saiyan Blue Vegeta, and you'll need to earn 500,000 Zeni to unlock Super Saiyan Blue Goku.
If that seems like a lot of Zeni, that's because it is. It's going to take any player a long time to earn that much Zeni, so patience is required.
It should be noted that you don't have to actually save up the required amounts. You can spend Zeni on capsules as you wish -- the 300,000 and 500,000 thresholds only apply to your total earnings across the whole game.
is that true ?