You need Chidori and Exciton. You don't need x2 Ark Knight, really. The deck itself rarely Xyz. Also x2 Bond isn't worth it for now because the deck already have bricking problems from their nature. Until we get more consistency cards, x1 Bond is enough. It's already searchable by Fusion Kanna.
Also, Tempest and Foolish Burial are both mandatory. Foolish to dump Tempest or to set up Rera play. Tempest banishes your monsters for more setup, and also special summon itself, it's a must.
Options that can be considered:
- Fiendish Chain/Breakthrough Skill
- Torrential Tribute: You'll always have Fusion Petolphin during your opponent turn. Using Torrent to destroy all their monsters while your monster isn't destroyed is quite evil.