I dunno why Diddy is so highly rated, seems really janky and unsmooth. Like, who mains the character? I saw Eli that 1 time vs M2K with Diddy, and I see Disco play him, but that's literally it.
Wario is fun, but his MU spread vs the top characters feels pretty bad. Falco Marth and Sheik feel really hopeless sometimes. If you are going off the survey list on page 63, I only think Wario does great vs Diddy and Bowser above him. Everything else seems debatable on whether he goes even or loses. Even below him, it doesn't seem like he has a particularly easy MU with Ike or Falcon or characters around that level. I really like Wario though, and I wouldn't change much about him, he's in a very good spot. He's a very capable character, that basically is just surrounded by some better characters. There aren't any (or many) fatal flaws to the character, and if you potentially buffed those areas, he would be monstrous and not as enjoyable balance wise.
The only aspect about the character that I do not enjoy entirely, is that a big portion of his gameplay can be based of "tricky" throws or tech chase options. Like, you can gain or lose a TON of options based on whether they correctly DI either bite toss direction, whether they DI quick Fthrow good, whether they CC tech Dsmash, etc. Some of it is fairly gimmicky and will be lose over time as people gain experience against the character, and the general rule of thumb is if you DI away from Wario's body that you picked the safest option. Regardless of character or weight/float. Compare that to characters that may have mixups or punishes regardless of DI.
Wario doesn't have as many BnB combos, but he has general pressure situations that apply to a lot of characters, and he can generally have a favorable RPS when he is on offense. He's more on the fly, where once you start a scenario you see how to play it out best and keep it going. I mean sometimes, something cheesy like Double Dtilt into JC grab is a combo, or you can catch people with bad DI on throws, but basically you get in and try to figure out what hit will work for that moment in time. With your air mobility and above average options up close, he's very capable of just "making it work" if you know what I mean. Like if they are a character that will have a hard time if they get offstage, you aren't too concerned about landing X move, you're concerned about landing any of 2-3 moves in that moment that will probably send them off, with you still in the driver seat of momentum. Plenty of times you won't have a true combo, but will have a huge advantage over them, which can be just as dangerous for that character.