Hatman is a magician but I don’t know much beyond that because he’s a japan only character. I don’t like japan only characters too much because I don’t get to see them fight first hand. But he still beats Rocketman. Hatman wins.
Flashman can quickly defeat Destroyah. Destroyah is pretty big but Flashman is a lot faster and can easily defeat him with his thunder skills. Flashman is just tough that way. Flashman is one of the strongest darkloids. Flashman wins.
Napalmman has napalm bombs that he can use to defeat Rocketman. Rocketman is so weak that no matter what strategy he does he will lose. That’s the sad truth. Napalmman is that much stronger than him. Napalmman wins.
Kaguro is a lot tougher than Toadette and can easily beat her. Toadette is just not one of the tougher characters. She can’t really fight and Kaguro can easily beat her.
Meddy is one of the weaker navi’s but even she can beat Rocketman. That’s why it doesn’t pay to only be in the anime. Meddy was in all 3 forms of media which helps her case. Plus she has crossfusion which would probably win. Meddy wins.
Morrigan is another character who needed a loss. Now she’s got one she’ll never come back from. Kaiba is arguably the Greatest Duelist and with more than a hundred cards she can’t defeat him. Kaiba tech rules. Kaiba wins.
Videoman is certainly not one of the better navi’s but he’ll have to do. Rocketman will still lose, but now he’s more than halfway done. Happy for him. Videoman is not doing great but not doing bad. Videoman wins.