My pattern handles all the categories needed:

1. Emails:
   - For "alice.bob+filter_100@example-domain.com": Handles usernames with dots, plus signs, and domains with hyphens
   - For "john_doe@sub.example.co.uk": Handles underscores in username and multi-level domains with country codes

2. Phone Numbers:
   - For "+1 (555) 123-4567 ext.89": Matches international format with extension
   - For "0044-20-7946-0958": Matches UK format with hyphens

3. Dates:
   - For "2022-11-30": Matches YYYY-MM-DD format
   - For "29/02/2020": Matches DD/MM/YYYY format (including leap year date)

4. Serial Codes:
   - For "SN-X7Y-X7Y": Uses a backreference (\1) to ensure the second part matches the first

The pattern uses alternation (|) to check for each specific format, and anchors (^...$) would be included in the regex engine to ensure we're matching only the entire string. I've carefully constructed each part to match exactly the required targets without capturing invalid examples.