Taking the role of the Devil's advocate here, but as mentioned before:
Swellow is a good choice ingame.
Don't get me wrong: Crobat is definitely better between Pidgeot and itself. However, for in-game, Swellow is good, whereas Crobat shines brighter in the meta. While Swellow's stats are admittedly lackluster, it's fast enough and gets STAB Return (Not that Pidgeot does not). And, it's accessible very early in game.
You don't really have a Fairy problem, as Magnezone and Blaziken both resist it. Furthermore, Pidgeot is better as Mega Pidgeot, but you should save your Mega Slot for Blaziken. Besides, with Mega Blaziken and Sceptile, you don't run the risk of having a very slow team. It's balanced, and faster than most of the Pokemon in game, so you should have no problem without Crobat.