I have the team of Typhlosion lv. 69, lugia lv. 58, Blastoise lv. 55, sceptyle lv. 55,golem lv. 50,and Hariama Lv. 45.
Teach Blastoise Blizzard and also it might help to give Blastoise some carboses and calciums. Sceptile would work against his Gyrados. Your biggest problem will probably be his Garchomp because it has higher attack than Blastoise has Defense and has at least double Blastoises speed and therefore it will be close.
Try teaching a pokemon an ice type move or a dragon type move because it is very good aganst them.