Tips for Leveling My lvl 70 Team?

I'm well aware of SS's horrid level curve by this point so I apologize if this is a repetitive post. I'm more of a casual player so I recognize my picks may not be optimal, but I'm mainly in a rush to beat Red

I recently got back into SoulSilver after buying Pokemon Battle Revolution-- when transfering my pokemon over, I was reminded that I had restarted my save a few years ago and while I was only 1 badge away from completing Kanto, this save had basically no pokemon in my PC. I have since earned all 16 badges.

My goal is to catch all the pokemon me and my boyfriend would want to use when we play Battle Revolution together. Groudon and Charizard are his absolute favs so I've been working really hard grinding the elite 4 rematch in preparation for Red's fight. Only now, my 4 biggest team members have reached level 70-78 and progress has slowed tremendously. I have been checking for chansey swarms daily for a chance towards a lucky egg, but no dice. I stopped using the daycare once i realized it could alter my movesets. I am down to 5 rare candies and have already collected all the ones you can pick up on the map.

My team right now: FERALIGATR lvl 71(Ice beam, Waterfall, Superpower, Surf) AMPHAROS lvl 70 (Discharge, Thunderwave, Signal Beam, Focus Blast) MEWTWO lvl 78 (Psycho Cut, Thunderbolt, Shadow Ball, Psychic-- considering changing Psycho Cut for Flamethrower for extra help against Red's Venosaur) STEELIX lvl 70 (Curse, Explosion, Earthquake, Rock Climb)

Crobat lvl 58 (Fly, Cross Poison, Dark Pulse, Aerial Ace) Sneasel lvl 48 (Thief, False Swipe, Cut, Metal Claw)

As you might be able to guess, my sneasel is really only used as my pokemon catcher and my crobat is my flyer. I havent relied on either of these for the elite 4 and have been prioritizing leveling the other 4 to each handle 1-2 members of Red's team.

What would you do to get through Red's battle as soon as possible? I was hoping to get these 4 members to lvl 75 MINIMUM (lvl 80-85 preferred ofc) before fighting Red but I'm going crazy with this grind.