Are you grinding for the gold mecha skins? Well, if you follow my way, you will get there. I'm not grinding for it, but here's my advice. This way you'll be able to get it in a few months instead of a year. It'll be hard, but a lot quicker than the easy way.
Ok, so you need to get all 28 brawlers to 1,000 trophies at rank 30. It's not too hard because the trophy loss isn't too high. In total, you'll get 42,000 star points. Then you simply get about another 15,000 because you probably bought the other star skins, and that shouldn't take too long because you are already at 1,000 trophies per brawler. So yeah, that's my advice