SD lucario wouldnt work too well as it learns extremespeed at lv 51, so unless there is some breeding trick i dont know about (if there is one can someone please give me details cause i need a lv 50 lucario that knows extremespeed) then it probably not have the same effect as a normal SD lucario
i also agree with a backup team, not a complete new team but more like pokemon you can interchange, for example- if you feel garchomp isnt working as a lead and u want a strong lead, consider using the standard azelf suicide lead set but instead of stealth rock run grass knot or shadow ball as it was said that rocks arent as effective in 3v3 and if it is like what i experienced in 07, the opponents dont always know what they are doing in terms of who they are using and what attacks to give them (i saw a rhyperior that was using ice beam and a golem using flamethrower, as well as some other strange pokemon choices like moltres and dragonair), so it is good to be able to cover a large amount of types due to the early round randomness