Runoff vs IRO

[DEMOREP1]

The relative rankings of the methods to produce a Condorcet Winner (CW) are
apparently--

1. Condorcet
2. Approval
3. Bucklin (sum votes at choice levels, 1st, 2nd, etc.)
4. Runoff (top 2)
5. Instant runoff (drop lowest repeatedly)
6. Plurality

Any more methods to add ?  Why even mention 3-6 when 1-2 exist ?