4th Gen HELP ME with my team stuff

[EthanandLuinor]

so currently I have a level 42 infernape, level 38 luxray, level 40 drapion, level 38 staraptor, a very under leveled level 30 Lucario, and a level 39 gastrodon, I have 7 badges and in the lake arc rn, because I have both an infernape and lucario i have a type situation, infernape being fire fighting and Lucario being fighting steel Idk if I should either replace Lucario or box Lucario and just have a team of 5, the leveling issue is that my highest level mon is infernape at level 42 and have to catch everyone else up to him, but it is going super slow, I need a lucky egg to speed this up but because I can only get a lucky egg through thieving chansey's all week, I need help, I need a solution of should I replace lucario with a different pokemon like weavile or box lucario and make it a team of 5, and how I get a lucky egg, please help

 

[Corveone]

Is this Platinum, Diamond, or Pearl?
Are you playing on console or emulator? (Because if you're on emulator, you should definitely try the 60 fps unlocker which makes Gen 4 games way more enjoyable)

Your team's most obvious issue is that three Pokémon are weak to Ground, so I wouldn't add Lucario or anything else that's also weak to that type. Maybe adding another Pokémon that's good against Ground would help balancing things, especially considering that one of the E4, and Cynthia's Garchomp, are Ground types.

Froslass:
Can outspeed and one-shot Garchomp with Ice Beam. Good against Ground and Psychic E4, and gives you an immunity to Fighting moves that none of your current mons resist. Medium fast growth rate so it's easy to raise in the late game.

Weavile:
Similar purpose as Froslass but faster and physical. However, you'll need shards to teach it Ice Punch for a decent Ice stab, and watch out for Psychic Pokémon with Fighting coverage.

A strong special attacker like Roserade, Gengar, Alakazam, or Espeon, could be also a good addition since your current team apparently has physical and mixed attackers, but not a fully special one.

Since you're almost at the end of the game, think about the E4 types and what you could add to counter them better. And avoid Pokémon with slow growth rates if you're finding the training process tedious.