My biggest issue with Loki joining was fans talking about Zoro/Sanji being weaker, but, I was just being dumb.
Mihawk's above Loki, and EOS Zoro will surpass Mihawk, clearly.
Even if Loki/Yamato join in the future, Zoro will be #2.
Once Zoro control his Adv CoC, and learns Ryuo, he'll be nearing his peak.
Also ZKK will give the Wado Ichimonji Kaido's Fruit, that will push Zoro over the top.
Yamato was Zoro's measuring stick for Wano, he'll surpass Yamato in Elbaph when he uses Adv CoC against the God's Knights.
Loki is Zoro's measuring stick for Elbaph; since Loki is Kaido's brother, Zoro killing Kaido in Act 4 will put him firmly above Loki/at Loki's level.
Zoro should be able to 1v1 Kaido to a good extent when we return to Wano for Pluton, and Fuji explodes, releasing Kaido and Linlin back into the beautiful Blue Planet.
If Loki joins, it will only be after Zoro surpasses him.
This is the biggest knock against
@Mr. Reloaded , here: as far as I know, Reloaded doesn't think Zoro will surpass Loki anytime soon.
@Mr. Reloaded , when do you think Zoro will surpass Loki?
Zoro will surpass Loki within the next arc. People just hate/underestimate how broken CoC, and Ryuo, are in this universe.
Pre-Adv-CoC/Ryuo Luffy couldn't damage Kaido at all.
Post-Ryuo Luffy made Kaido bleed from the mouth in Base with Gear 3 and Ryuo.
THE SCABBARDS damaged Kaido with Ryuo, when Yamato couldn't, because Yamato has Adv CoC, but no Ryuo to get through to Kaido (Yamato's current power up will be learning Ryuo from the Scabbards).
Post-Ryou Luffy couldn't 1v1 Kaido at all, got bodied everytime he tried.
Post-Ryuo/Adv-CoC Luffy was 1v1ing Kaido for extender periods in Base without using Gear 3 that often.
People just don't realize what kind of problem Zoro's going to be with Adv CoC/Ryuo.
Add in a Seastone Blade + Kaido's Fruit in the Wado, and the Zoro is literally the Admirals' worst nightmare.
Zoro will be Top 5 by EOS. He might honestly end up the 2nd strongest in the entire verse...