Gardenia, Lantana, Laurentia, festival/yukata Dogwood and Evening Primrose are all 5* Knights with bloom forms and a solid mix of abilities. If you happen to have all five in the same squad then once they're bloomed they provide:

• 2x skill proc rate (each Knight has 1.2x skill proc rate and the boosts stack additively)
• Turn 2-3 normal/blank panels into chocolate healing panels (Lantana)
• Increase number of pests hit by cannon nodes by one (Gardenia)
• +60% attack power for the squad (10% each from Lantana, festival Dogwood and Evening Primrose, 15% each from Gardenia and Laurentia)
• +10% shine crystal drop rate (Laurentia)
• Squad recovers HP equal to 10% of max HP when clearing a pest nest panel (Evening Primrose)
• Counterattack 80% of the time with attack power equal to double her defense stat (festival Dogwood)

Swimsuit Toad Lily doesn't have her bloom form (yet) but she has +10% crit rate for the entire squad as an ability if you're looking for a non-6* crit booster. If you go to the trouble of getting her skill to level 5 then swimsuit Toad Lily also adds 18% attack power for the entire squad which is a boost normally reserved for 6* Knights.