Dialga's Strengths:
* Primal Dialga is extremely powerful: It has incredibly high Attack and Special Attack stats.
* Dragon and Steel typing: It's resistant to a huge number of moves, including most common Grass, Fighting, and Normal type moves.
* Powerful moves: It can learn moves like Draco Meteor, Iron Head, and Roar, which can easily obliterate Turtwig and Riolu.
Turtwig and Riolu's Weaknesses:
* Low stats: They're both relatively weak and frail, especially at low levels.
* Type disadvantages: Turtwig is weak to Fire, Flying, Poison, Bug, and Ice. Riolu is weak to Flying, Psychic, and Fighting. Dialga hits both hard.
Strategies (with low chance of success):
1. Focus on Speed: Train Turtwig and Riolu as fast as possible. Prioritize moves that increase Speed or lower Dialga's Speed.
2. Use Status Ailments: Try to inflict status ailments like Burn, Freeze, or Paralyze on Dialga. This will help reduce its damage output.
3. Utilize the environment: Use terrain effects (like Grassy Terrain for Turtwig) to your advantage.
4. Exploit weaknesses: While few, Dialga is weak to Ground and Fighting types. If you have access to any items that change type (like a type-changing berry), this could be useful.
5. Bait moves: Try to bait Dialga into using moves that are weak against your Pokemon's type.
6. Pray for luck: You're going to need a lot of it!
Important Notes:
* Level matters: You'll need to level your Pokemon significantly higher than Dialga to have any chance.
* This is extremely challenging: Even with optimal strategy, the odds are stacked against you. It's highly recommended you consider adding other Pokemon to your team.
In conclusion, it's very difficult to beat Primal Dialga with just a Turtwig and Riolu. It's recommended to have a more balanced team with stronger Pokemon and a variety of types to stand a chance.