Yahoo UK and Japan: Contact information for Title and Description
Contact information, even telephone number is not allowed to contain for Yahoo creative.

• Display of URL
• Email
• Telephone number
• Contact physical address
• Contact address or other similar type information

Yahoo Japan: Competitive Claims for Creative
Although comparative information in competitors' products and services are not allowed to use for Japanese Yahoo title and description, Google allow competitive claims in an ad text. It must be specifically supported on the landing page.

Google’ supports can be those examples;

• Charts or Tables: which compare the features of a product / service vs. a competitor's product.

• A Competitive Analysis: discussing why this product is superior. If the landing page includes a competitive analysis of the advertiser this claim would be acceptable and the ad would be approved.

*Yahoo Search marketing UK noted only that “if your listing contains competitive claims, make sure your site and title and description all meet our Trademark Policy”.

The guid lines for yahoo is more helpful.Yahoo give a some what different search than google.