Earth Eagle is the best buy-able bey, but if you have a good stamina performance tip and a Earth Eagle fusion wheel you might be able to customize an even better bey.
It's because of the lag. Some leechers click save and while it's loading for the image enter battle. This makes the bey invisible, and you have no idea where its going to hit you.
There are no most powerful beyblade. The most powerful beyblade is the one you trust for, care for and the one that you will always fight by. Do not get convinced that one is the most powerful...