All you need is pokerus, and a macho brace (for the first time).
When you have an EV trained team, you can take 3 of them to the Battle Tower, and try to beat the Frontier Brain, and get the power items, which are better than the macho brace.
When you have an EV trained team, you can take 3 of them to the Battle Tower, and try to beat the Frontier Brain, and get the power items, which are better than the macho brace.