1) The situation with 2 "A" and "B" products. This one is pretty easy.

We need to create SD campaign with the product ad for listing "A" and target listing "B" inside the campaign. Then we need to make the reverse campaign with the product ad for listing "B" and target listing "A" inside the campaign.

Listing "A" may be your listing or your competitor's listing that you want to attack.

Campaign → Ad "A" → Target ASIN "B"

Campaign → Ad "B" → Target ASIN "A"

Note! Inside Sponsored Display, you can create only one ad group per one campaign.

2) Okay, let's go to the nitty-gritty—the second situation. We have three products, "A," "B," "C".

The structure for protecting your listings would be:

Campaign → Ad "A" → Target ASIN "B&C"

Campaign → Ad "B" → Target ASIN "A&C"

Campaign → Ad "С" → Target ASIN "B&A"

3) The third situation with four products. A, B, C, D+

Campaign → Ad "A" → Target ASIN "B&C"

Campaign → Ad "B" → Target ASIN "A&C"

Campaign → Ad "С" → Target ASIN "B&A"

Campaign → Ad "D" → Target ASIN "A&B"

Campaign → Ad "E" → Target ASIN "A&B"

You need to determine your top 2 ASIN's, this ASIN will be the targets of A&B listings and keep targeting other listings.

NOTE! Coupon codes (5-10-15%) works fantastic with sponsored Display and increase CTR significantly.