alrighty. I finally got hozukimaru to hogyoku-kai and I used him in a battle and it looks like he just doesn't give bonuses to assaulters. he gie damage rates for the entire team for 2 rounds. he aint bad. might get more use in pve then pvp. also could be better the zabimaru. also for the bonuses for reiatsu it looks like hozukimaru would be better then tengen.
extra reiatsu bonuses:+120% tengen: vanguard: damage: -20%. avoid: +18%. HP:+60%. Revival rate:+40%. assaulters: speed: 12%. damage rate: 12%
extra reiatsu bonuses:+120% hozukimaru: vanguard: damage:-40%. avoid:+18%. HP:+60%. revival rate:+40%. assaulters: speed:18%. damage rate:21%