Speaking personally, the one weekly circuit that's helped most with both pickleball elbow and my Achilles is a simple tendon-focused session I keep away from match days. I usually do it once a week, about two to three days before competition, so it supports play rather than interfering with it.
For the Achilles, I use single-leg calf raises on a step with a slow tempo. It's usually bodyweight plus a light dumbbell, three sets of six to eight reps, taking three seconds up and four to five seconds down. I only increase load when everything feels calm for a full week, and even then the jumps are very small. That slow lowering has been key for keeping stiffness under control.
For the elbow, wrist extensions with a light dumbbell have made the biggest difference. Forearm supported, three sets of ten to twelve reps, slow and controlled, nowhere near failure. I'll sometimes add light pronation and supination with a hammer, again very controlled.
I finish with something like split squats or step-ups for general lower-body support, kept light and tidy. Around tournaments, I don't remove the circuit, I just halve the volume. The goal is always to feel better the next day, not trained.