Main strengths: Hard to kill, Great area control with her Defense matrix, Good damage output from short range, Can win most 1v1s, Double life (mech), Great objective protector.
Main weaknesses: Occasional and predictable ultimate, No long range damage, Has viable counters
Favourtable maps and modes: D.Va is fit for most maps and modes but excels when protecting or attacking through choke points.
Defend / Attack specifics: As defender you need to time your Defensive matrix properly to block damage. Stay in the frontline when its up and get a bit back when it's down. As attacker you need to be the guy making the push (possibly with Reinhardt). Providing safety for your backline is essential.
Synergises with: Ana, Reinhardt, Mercy
Countered by: Zarya, Mei, Reaper, Genji, Reinhardt