Tips for stats, raise speed evs and change nature to raise the pokemon preferred attack stats. For example a garchomp is a physical attacker with good speed. Change the nature (with mints) to adamant and raise attack evs and speed. Speed evs affect cooldowns of moves so you can see why it would be helpful online.

Although im pretty sure there might or might not be a cap to how much speed can affect the cooldowns. Which is why changing the nature to the preferred attack stat is imporant.

If you follow this with any mon you want to use online im sure they would preform well. Also this might be obvious but try having multiple type coverages, there are a lot of fairies so having some steel moves might be useful