1.Stats: Should Flygon get a stat boost, Evolution, Mega Evolution or nothing?
As a three stage species, Flygon cannot get an evolution, and as a mid-game species with relatively weak middle stage that has been relatively available throughout generations, one should not expect much from Flygon. What Flygon really needs is that its stages match that of its level, with Trapinch gaining +10 BST, Vibrava gaining +50 BST, and Flygon gaining +20 BST.
But overall, a stat boost for 10 to 20 BST, likely focused on Flygon's Special Attack, seems the best bet.
A Mega Evolution would still be necessary, as Flygon is an overtly balanced species. A Mega would be able to better min-max its stats so it can see other uses besides utility and scouting.
2.Should Flygon get more abilities?
Yes, though Trapinch has three powerful abilities, its evolutions are stuck with Levitate. Bringing Arena Trap and Sheer Force to Vibrava and Flygon would help them immensely.
Other sand based abilities like Sand Stream, Sand Veil, Sand Force, and other abilities like Contrary and Tinted Lens would also be fitting.
3. Should Flygon get more moves?
Yes, though Flygon got the move it was missing most, Dragon Dance, other moves like Swords Dance and Quiver Dance can also be granted. Moves like Air Slash and Hurricane, and Acrobatics can also be granted.
4.What additional typing Flygon can have?
Bug and Flying are the most obvious choices, followed by Rock, Dark, Normal and Fire. Fighting and Grass are also lesser options.