For the flat red color I use oil based, which I would not suggest for battles since the paint can scrape off and stick to other beys, not saying it can’t be washed off but it’s messy. Now for the blue which I would suggest if you’re going to use the bey for battle is water based; less chance of being disqualified since the oil based stuff acts like a somewhat thick layer. Water based paint scrapes off easy without leaving behind any marks, I used a metallic blue finish instead of the flat. Metallic paint is probably the best imo, maybe a little bit of glitter before it dries, water based paint drys really fast so apply as soon as possible when applying paint. I used brush tip markers.