50 + Farts - 50
I play both characters and have a slew of matches against leoftw. The only thing Wario has a significant advantage over Kirby with is the fart. 80% kill move (l2DI) beats 120% kill move and is easier to land. Kirby can jump out of most of Wario's early combos and Wario can DI out of Kirby's grab thingy pretty well, but never discount d-tilts and up-tilts for building damage. Wario counters that damage building with his d-air, forward throw and bite.
For kills, nobody's f-smash is killing anybody (except for pro kirbies that get their grab hits :!!), tell me why you still can't DI. Half of my kills are refreshened back-airs at like 150, the other half are forward smashes when you Wario lands on the ground near me off of an airdodge or beating out a SH attack, around 120 fresh. Wario kills me around the same % with his forward smash, but I learned to recover high and not do shenanigans (rock, smashes) until he starts flashing because at mid height off the stage you have to waste a lot of ****ing time to not get farted on and if you have to Up-B you still get farted on. Airdodges, spotdodges, everything, try to scare the Kirby after they miss something up and get that 80% fart off, because how the **** is Kirby going to hunt you down and kill you if you play runaway/chip a stock up?
I think everyone else in the thread is underestimating Kirby's ability to wall out Wario. Wario enjoys a lot of "priority" in this game just because of his high airspeed and fallspeed. Wario's attacks beat out traditionally high priority characters like Marth and Meta because they just get out and get in range faster. Kirby's b-air and up-tilt are too fast and too meaty (they last a long time). Jump around, space, anytime you feel threatened, FF B-air. It beats everything Wario has and is only punishable when Kirby ****s up. If Wario tries to follow up you can time an up-tilt (easily). On the ground up-tilt and f-smash beat all direct approaches when timed correctly, and OOS b-air punishes most of your moves and is safe. Wario needs to mindgame to break this wall and Kirby is at a strong advantage when at low percent and Wario's fart is on cooldown.
Kirby can also press a stage advantage with backairs and force Wario to either try to jump over him, attack, or back up to the edge of the stage. Wario needs to get above Kirby to be effective and is better on stages like Smashville while Kirby is better on stages that limit Wario's space and approaches like Battlefield, and they trade fairly evenly on FD. Wario should bait for grabs often and not be overly aggressive, and try to land powershields and gg with wafts.
Oh yeah, and edgeguard Kirby like a ****ing champ if he recovers low. Come from above and just force jumps with D-air and just don't get swallowcidered and you're good. Kirby's airspeed is literally 1/3 of yours and he won't be able to chase you back to the stage so you can get some cheesy edgehogs sometimes.
55-45 Wario at high levels. 60-40 Kirby if Kirby never gets wafteded.