Team synergy Help

Generally a team comp is 1 DPS 2 supports up front 2 fillers behind them to take over when a frontliner dies and a survivor like herc, cu, or nero in the last slot in case things go wrong.

Most gold servants work as good DPS so just use whatever has class advantage. For support Hans and David are great low rarity servants and Nightingale is a underated buster support largly due to being overshadowed by Merlin. Other useful common servants would be Leonidas, Georgios, and Mash who are all great to switch in and taunt against bosses single target NPs Leonidas being the more offensive option for buster teams while Mash and Georgios offer better defensive options.

Your supports are nightingale martha and mashu. You want servants who can make use of defense and heals. So emiya is a good dmg dealer since he has an evade. You lack a lancer and caster. Get leondias shakespeare and medea.