Wild pet team makeup seems to be pretty much random. When you see a pet you want to capture, its backup will be two more of the wild pets found in that general area and that backup will vary from one target pet to another. You don’t have to worry about the sort of Trainer teams that have been carefully designed to supplement each other and can be nasty fights.
I’ve had excellent results from a general purpose team, starting with a non-killing ability pet like the Turnip or one of the dogs with Superbark. Other two depend on what you’re comfortable with – I use Chrominius and Feline Familar – but I’ve very rarely had to change that backup for a particular wild pet battle.