If you use paladin for lvl 30, don't attack his monster. Put some draw card if you can to avoid him deck out. For lvl 40 I don't recommend using paladin because he can mill really fast. Hazy is better choice for lvl 40. You can destroy his monster every turn with hazy
For Dark Paladin deck: with 1 additional card "Gravedigger Ghoul". Use Restart to get Dark Paladin out 1st turn and its smooth sailing till the end. Don't attack his Monsters. Use Gravedigger Ghoul only when he has over 2 Skull Servent/King of Skull Servants in the graveyard. I usually wait till he drops a 3rd one. Finish with the usual 🔥 cards for over 10K damage.