I’m mainly a (male) mixed-doubles player, and slow shuttles can completely ruin the game. If you’re able to force the opposing lady to the back, the rally is instantly over, as they simply won’t have the strength to hit a deep clear, guaranteeing you an easy kill on the next shot – but it’s a cheap tactic and won’t feel rewarding. My partner also says that playing with slow shuttles hurts her shoulder, so it’s just not worth it, and I always carry a few tubes of shuttles in my bag these days, purely for when this situation arises.
Assuming you’re stuck with the slow shuttles though, and not permitted to “tip” them to alter their speed, I think there are two main things to bear in mind:
1. Your smashes will be slower and far less deadly. This means you need to be more patient, and build the point to set up a more clearcut attacking opportunity, by using more variety, placement, deception, etc. You cannot rely on power alone, and if you keep hitting jump smashes from the baseline, they’re going to keep coming back, and you’ll just get tired. However, when you do get a good opportunity, you must go all-out to take advantage – one slightly weak shot could allow your opponents to play a good lift, undoing all of your hard work. This is where slow shuttles favour big-hitters, as they require less of an opening before they can launch a decisive attack.
Of course, all of this applies to your opponent(s) too, so you should be more willing to lift when under pressure. Defensive shots are much easier not only because the shuttle will be coming at you more slowly, but because there’s little risk of you hitting them out the back of the court.
2. It’s much harder to get good length on your clears, so you may need to hit them a bit flatter. On the plus side, length is less crucial – slightly short clears are less likely to be punished, and you probably won’t be hitting them out the back. Again, it’s the same for both (all four) players, but if you’re physically stronger than your opponent(s), you have the advantage with slow shuttles, and you’ll probably want to play more attacking clears and keep them pinned at the back, to wear them out.
If you have significantly less power than your opponent(s), you’re going to have a rough time… good luck.