Complex sentence: In the OVA, Ukyo and Shampoo thought of the idea together and the rest of the cast had come along, but it was the same disastrous result for Ryoga and Ukyo.
Split into simpler sentences: In the OVA, Ukyo and Shampoo thought of the idea together. The rest of the main cast joined the trip as well, but it was the same disastrous result for Ryoga and Ukyo.