I enjoy making money, and I do Le Wow and the Battle Chateau. Then while exploring, I came across the 4th restaurant, Sushi High Roller. With the money I had, I went in there and completed a run, and I realized I lost over 100K. Is there any to get enough money to make more than 500K with the battles and the big gold nuggets?
There is no way possible to come out of Sushi High Roller with a profit. Even with Max Style + Amulet Coin + Lvl 3 Prize Money O-Power the numbers run like this:
Entry Fee (With Max Style) = $450,000
What you get:
Prize Money (With lvl-3 O-Power & Amulet Coin) = $160,000
Big Nuggets * 25(Best possible) = $250,000
Total winnings ~ $410,000
That is still a net loss of -$40,000. So Basically it is not worth going in there for money, unless you want a completionist record for starring all the battles, or the Exp.
There is no confirmation of the Entry Fee going any lower, for it to become profitable.