It's not situational at all. Lucario has less hard counters than Keldeo, who resides in S. Keldeo requires support to even have a chance of getting past its counters. It's counters are nowhere near as ubiquitous as Keldeo's, and even Lucario's counters, like Jellicent for example, need to watch out for Lucario's coverage moves. While it requires a bit of scouting to use Lucario, it requires even more scouting to beat Lucario. It's versatile movepool means it can be unpredictable and very hard to beat. It's much harder to revenge than other A- rank Pokemon, as Salamence is easily revenged by Scarf Terrakion and Mamoswine. Gengar is destroyed by strong priority or scarfers, and Dragonite is killed by any scarfed Dragon or Mamoswine again. Also, the stealth rock argument is a joke. What do you want, for it to be immune to it? It takes the lowest possible damage from it. Only Pokes with Magic Guard are immune to Stealth Rock. It doesn't exactly have a crippling flaw like Volcarona for example, and its bulk is actually better than Breloom's. I just want to know how exactly it doesn't fit the definition for A rank: A Rank: Reserved for Pokemon who can sweep or wall significant portions of the metagame, but require some support or have some flaws that prevents them from doing this consistently. This fits it better than the definition for B rank: B Rank: Reserved for Pokemon who cannot sweep through or wall significant portions of the metagame, but can properly fulfill a given offensive/defensive niche. It can sweep through the majority of the metagame. To say it can't is false.