I'll just give you a 'standard' sun team. You need Mandibuzz on your team. If you don't have Mandibuzz, Dragapult will rip you apart and Garchomp threatens to destroy your team completely. Mandibuzz can handle both dragons and Kartana. Offensive spdef Chomp allows you to handle opposing Heatran who can easily predict your own Heatran and earth power. Chomp also just enjoys the sun as it powers up its fire moves. Scizor is your steel type. Be very careful about this as it gets roasted in sun and basically, it just serves to handle Lele. You do not want Mandibuzz to get overwhelmed. Also, don't use Charizard. That mon ******* sucks. Every other sun abuser outclass it thoroughly
https://pokepast.es/84b4094bd8209fc6
For your main sun abuser, just pick among these. Volcanion would provide you with a crucial water immunity while specs eruption Heatran under the sun is the strongest attack in out. It even melts offensive Garchomp and Victini does Victini things
https://pokepast.es/18b83e04735afd26