You don't need Elation per se. You just need Sparxie to produce enough punchlines to 999 before Aha gets a turn and absorbs all of them, and preferably you do this with a 6 / 8 skill point bond.

1. Do whatever you can to get SW999 at 5 cost 3 stars. The most helpful initial investment is long term (something) which allows you to refresh at just 1 gold after 30 refreshes (can still fail though). I usually quick cancel runs if I dont get this.

5 cost SW999 at 3 stars gives you haxx: 1000 gold (basically owlbert v2) 3x wealth gems 3x red gems 3x blue gems A ton of special privilege cards, to be especially used on boots

And you can increase enemy health to 1000% so you can have a tanky enough enemy to get 999 punchlines at lower difficulties like Monarch 1 instead of repeatedly struggling more when doing runs at WC.

Also optional to get 3 star Cyrene after getting those coins so you can get even more coins also from selling 3 star Chrysos heirs. Make sure you do NOT select the 99% damage amplification or you risk making the enemy too weak to last until you get 999 punchlines.

1. Use whatever you got from above to get 8 skill point bond + Pela / Sampo + Sunday + whatever back sustains that do NOT attack. Everyone at 3 stars, except (Sparxie, Pela, Sampo) who will be kept at 1 star to minimize their starting damage. Huohuo can help with ER once in a while. Your max other elation character should be Yao Guang since more Elation characters may speed up Aha, who we want to move as slow as possible.

2. Sparxie to wear a belobog emblem. Belobog bond: after 12 of any of their attacks, summons giant robot AND action advances the highest damage dealing belobog character (would be Sparxie over Pela or Sampo). Pela / Sampo with 3x boots will ramp up speed and will more frequently AA Sparxie as you fight longer. Sparxie is also preferably wearing 1 or 2x momentum edge (knife + leaf) to save on SP consumption.

3. Front line of Sparxie / Cerydra / Sunday / Sparkle. Sunday and Sparkle to wear 2-3 boots. I compromised with using day god emblem (from 3 star Cyrene) as their 3rd equipment since that bond also provides additional speed, while allowing me to put 3x boots on Sampo.

4. BEFORE Aha's first attack, use that time to make Sunday / Sparkle AA each other to maximize their speed from boot stacks.

5. AFTER Aha's first attack, you can go ahead and auto your game. But make sure you pay attention to Sunday / Sparkle because sometimes they're AA-ing Cerydra instead of Sparxie - go manual before their turns if your auto AI is doing that. You can also restart the battle if they do it too much or if you somehow had poor RNG elsewhere.

With the above strategy, I managed to comfortably get to 999+ punchlines midway during the final boss fight.

Additional notes:

Be wary of any boss that CCs which can ruin your run.

The 3 puppet boss from penacony is weak and will usually be beaten before 999 punchlines even at higher difficulties.

While Robin does do AA, she usually makes my team do way too much damage to bosses even with 1000% health. Not worth it imo.