I see many people suggesting putting all of your attack+ food items (ham) on Matt. However, Matt does not have any good multi-target abilities, and he uniquely has the best buff in the game: Temper. Temper buffs its target's attack by +70% and gives them the Brave status, which boosts crit to (base * 2) + 20%. Base is usually 10%, which means Temper increases crit to 40%. However, Anna's Arrow Rain and Combo shot have a base 20% crit, meaning she gets boosted to 60%. Piercing Shot has base 30% which becomes 80%.
So, a very easy playstyle is to have Matt go first, buff Anna with Temper, and then have Anna use Arrow Rain to wipe out the enemies. Anna can often wipe out the weaker enemies, if not the entire wave, in one attack.
Matt's Swift Slash is weak compared to Anna's Arrow Rain, and trying to buff himself with Temper means the enemies will get an attack off before he can get an attack in, and one turn of the buff's duration will be used up by the time Matt gets to attack.
Beyond Arrow Rain and Combo Shot, Anna has good weapon-elemental attacks that synergize well with each other. Aqua Arrow gives a long-duration Wet status which amplifies the damage of both Frost Arrow and Spark Arrow, which have good status effects attached. So it's good to keep her attacking.
Relegating Matt to being a buff-bot results in smoother gameplay than having him either spending a turn out of every 3 casting Temper on himself or going without the Brave status.