@CaptainXtra
The common arrangement for MLP-TF2 comparisons are usually as it goes.
Pinkie Pie - Pyro
Rarity - Spy
Rainbow Dash - Scout
Twilight Sparkle - Sniper
Fluttershy - Medic
Applejack - Engineer
Metal-Kitty was an artist that used a different comparison point (one that was apparently often criticized, he actually has his artwork in derpi). He only liked two out of those six (Scout Dash and Rarity Spy because they do indeed fit), so he decided to make a change into the dynamic.
The changed arrangements are:
1.- AJ - Demoman (literally the only connection was “Texan accent”, he thought AJ is too hands on and not really made for inventions or even complex engineering and math.)
2.- Pinkie - Engineer (Admittedly he found the Pyro Pinkie too easy, this one is the oddest one but Pinkie does use party gadgets but I concede this one is arguable.)
3.- Twilight Medic (Fluttershy being medic used the archetypical “gentle healer” approach…problem is TF2 Medic is a cackling goofball with little to no respect for nature and far from shy is actually rather proactive and aggresive, which fits better with Twiligth’s liking for scientific approaches and sudden bursts of insanity mixed with methodical wackiness)
4.- Flutter Sniper (he finds Fluttershy hard to fit into TF2 to begin with, but Sniper does has bushman naturalist traits and is the most inclined to attack from away rather than get personally involved).