It's a funny line from Luffy for sure. G5 Luffy power-wise and personality-wise is definitely fun.
As for Zoro, it ain't that bad. Luffy wrecked Lucci prior, he's just joking that he can lend a hand since he's kinda already proved himself against said opponent twice now. Zoro will be the one to put Lucci down for the rest of the arc anyways and doesn't need the help.
As for Kizaru, yeah, he got chucked hella far. It was decent move by Luffy to get rid of the opponent momentarily when they were at his mercy so his allies could flee but Kizaru is just so resourceful he took advantage of the throw by responding with clones and targetting Luffy's allies far from Luffy (but Luffy responded hella quick to them and intercepted the laser so good showings all around). Plus that throw was never gonna put him away. It's clear both Luffy and Kizaru are getting moments against each other that make them look good but hopefully Oda lets us see them give each other some good blows 1v1. I want to see just what Luffy is gonna bust out G5-wise and what Kizafy has in his bag.
Overall, yeah, it's a nice flex from Luffy.