$ pub outdated --json
Resolving...
{
  "packages": [
    {
      "package": "foo",
      "current": {
        "version": "1.2.3"
      },
      "upgradable": {
        "version": "1.3.0"
      },
      "resolvable": {
        "version": "1.3.0"
      },
      "latest": {
        "version": "1.3.0"
      }
    }
  ]
}

$ pub outdated --no-color
Resolving...
Dependencies  Current  Upgradable  Resolvable  Latest  
foo           *1.2.3   1.3.0       1.3.0       1.3.0   

dev_dependencies: all up-to-date

transitive dependencies: all up-to-date

transitive dev_dependencies: all up-to-date
1 upgradable dependency is locked (in pubspec.lock) to an older version.
To update it, use `pub upgrade`.

$ pub outdated --no-color --mark=none
Resolving...
Dependencies  Current  Upgradable  Resolvable  Latest  
foo           1.2.3    1.3.0       1.3.0       1.3.0   

dev_dependencies: all up-to-date

transitive dependencies: all up-to-date

transitive dev_dependencies: all up-to-date
1 upgradable dependency is locked (in pubspec.lock) to an older version.
To update it, use `pub upgrade`.

$ pub outdated --no-color --up-to-date
Resolving...
Dependencies  Current  Upgradable  Resolvable  Latest  
foo           *1.2.3   1.3.0       1.3.0       1.3.0   

dev_dependencies: all up-to-date

transitive dependencies: all up-to-date

transitive dev_dependencies: all up-to-date
1 upgradable dependency is locked (in pubspec.lock) to an older version.
To update it, use `pub upgrade`.

$ pub outdated --no-color --pre-releases
Resolving...
Dependencies  Current  Upgradable  Resolvable  Latest  
foo           *1.2.3   1.3.0       1.3.0       1.3.0   

dev_dependencies: all up-to-date

transitive dependencies: all up-to-date

transitive dev_dependencies: all up-to-date
1 upgradable dependency is locked (in pubspec.lock) to an older version.
To update it, use `pub upgrade`.

$ pub outdated --no-color --no-dev-dependencies
Resolving...
Dependencies  Current  Upgradable  Resolvable  Latest  
foo           *1.2.3   1.3.0       1.3.0       1.3.0   

transitive dependencies: all up-to-date
1 upgradable dependency is locked (in pubspec.lock) to an older version.
To update it, use `pub upgrade`.