I prepared about 40+ Jetdragons, some of them have 4 stats (Legend, Divine Dragon, Musclehead, Ferocious) and some of them don't. Those JD having 4 stats are also upgraded to at least 1 star.
In the middle of the fight, I replaced those incapacitated JD.
Beginning of fight, I rode Chillet with Vanguard stat.
After Bellanoir Libero (Ultra) regened HP, I rode Ragnahawk with Vanguard, Stronghold Strategist stats.
Both Chillet and Ragnahawk are also at least 1 star. Attack while riding them, greatly increased my damage to Bellanoir.
Above all, I also ate Cheeseburger before the fight to increase my attack.