If you're going to be using Kirby paired up with Link, your main goal should be to let Link do most of the fighting and, odd as it sounds for Kirby, try to life tank as much as you can. Your main job is to keep Link alive by interferring with other characters who would otherwise combo or gimp Link.
Seeing as Link likes to keep his feet firmly planted when edge-guarding, get on that ledge and take Edge Hog initiative. Drop off and ward off recovery with b-airs and have Link Edge-Protect you (keeping the second opponent away from the ledge).
Keep low to the ground and evasive. If you're mindful of your partner, Kirby will be very unlikely to ever KO Link should one of your attacks go awry. And - unless you get knocked into d-airs, F-smashes, etc - Link won't be likely to hit Kirby with anything dangerous. This will give him more room to breathe and take offensive position. Use d-tilt and f-tilt to either knock opponents off the ledge or toward Link where he can catch them with something more effective.
You can use this crouching tactic in various ways. Crouching next to Link as an opponent tries to recover should allow you to sneak in a d-tilt at the same time Link uses Spin Attack making for an awesome team Edge Guard. Ducking under his hookshot, arrows, bombs, and boomarang give Kirby cover as he approaches.
Link recovers slowly, and can do a good job at stalling with bombs and hookshots. Keep your eyes open for his return and clear the edges for him. If that's risky, you can always jump out and attack him (he should be aware of this ahead of time, seeing as he's partnering with Kirby) - use Copy, or even n-air -> wall-tech, and other attacks as the situation calls to give him a second chance should he fall short in his recovery.
Kirby's horizontal recovery is next to worthless without his jumps. Link can help out by throwing bombs for you to hit, sending Kirby up and allowing DI toward the stage as well as another chance at Final Cutter.
