Lol why the hell are you even comparing Mega Pidgeot to Talonflame and Mega Altaria? By your logic Tornadus-T is outclassed by Talonflame because Tornadus-T is also outsped by Weavile and struggles a little with Heatran if not running Superpower. There's no such thing as Talonflame and Mega Altaria outclassing Mega Pidgeot as otherwise Mega Pidgeot wouldn't even be ranked - Mega Pidgeot's niche lies in being able to fire off perfectly accurate Hurricanes which also somewhat allows it to bullshit through stuff like Heatran, an excellent Speed tier (which Mega Altaria lacks), good utility in Roost, Refresh and Work Up, good Fire-type coverage to complement Hurricane, and the ability to pivot with U-turn. Granted, Tornadus-T kinda gets in the way because on paper it seems as if Pidgeot is inferior to Tornadus-T, but Pidgeot actually has stuff like Hyper Beam, Refresh, Work Up, No Guard, and Roost (which Tornadus-T doesn't use), which let's it terrorize balance and stall more easily due to the utility of Roost, Refresh, and Work Up and the ability to get past various Electric-types such as Rotom-W and Raikou with Hyper Beam, so Mega Pidgeot has a solid niche over Tornadus-T. Heatran isn't a problem for Work Up Mega Pidgeot, which beats it. Mega Pidgeot can also pivot out with U-turn on the switch to something that beats Heatran such as Manaphy, Keldeo, or Conkeldurr. I'm more or less neutral on Mega Pidgeot's placement even though I've used it to a lot of success over the past few months but it's sure as hell looking better than half the things in C+, such as Alomomola (which is pretty bad and could potentially drop, not sure if it's on the level on Mega Absol in terms of viability though), Cobalion (decent pivot I guess?), and Cresselia (lol), but definitely inferior to stuff in B-, such as Infernape, Lucario, and Sylveon.
Alfalfa sorry if I didn't make my post completely clear, but Work Up Mega Pidgeot is a stallbreaker and wallbreaker in a sense. It works a little like Swords Dance Weavile and Calm Mind Latios - stuff like Tyranitar and Raikou aren't even legitimate answers mid- to late-game when weakened a little and Mega Pidgeot has accumulated a boost or two.