As in just the Evil Dragons?
Liang Xing Long (Haze Shenron) is hard to place due to him being very inconsistent. On one hand, he was injured by a rock and was compared to Mr. Satan by Goku, yet was then able to take hits from an Enraged Pan prior to his corrosion ability taking effect. Given GT's scale of power for most characters though, along with the supreme power of rocks and buildings in Toei works, I'd mainly take the latter into account along with Goku just calling him weak, with the Satan comparison being mainly to do with personality. At bare minimum, I'd place him above Freeza and #17/18.
Wu Xing Long (Rage Shenron) was capable of wrecking Base Goku with ease with just 50% of his electricity, which via scaling from SSJ Goku > SS2 Vegeta > Super Oob during the Super #17 Arc, makes him dozens of times greater than Gohan Boo and several times greater than SSJ Vegetto at bare minimum. He also seemed to be of some relevance to SS4 Goku iirc, so I'd say he should at least be comparable to Super #17 prior to absorbing SS4 Goku's Ki.
Liu Xing Long (Oceanus Shenron) was capable of clashing with Base Goku for a while before being overpowered, and even then, it wasn't a stomp. Based on Goku's later base feats in the arc, he was probably far stronger than the one the previous two dragons faced also. In line with the previous comparison, I'd scale her to around 50% of Wu's power or so.
Qi Xing Long (Naturon Shenron) was able to withstand several punches from SS4 Goku, something Goku even commended him for, which by default should place his Mole form far above any of the previous dragons apart from perhaps 100% Wu Xing Long. With Pan absorbed, he should be vastly stronger than that, especially to have stomped SS4 Goku, however drained of Shouki and Yuuki he may have been. At his peak, he ought to be comparable to Initial SS4 Goku's full power and Golden Oozaru Baby.
Si Xing Long (Nuova Shenron) was stated by Goku to be far above the previous dragons, even in his base form, which should place him above Golden Oozaru Baby for me. His true form was capable of fighting evenly against SS4 Goku and stomping a heavily drained SS4 Vegeta, so his power ought to rank just marginally below SS4 Goku's prior to going beyond his limit. After being revived, it was somewhat implied by Yi Xing Long that he'd become stronger, which from his feats against Vegeta, ought to place him close to base Yi Xing Long imo. His strongest attack is also capable of killing Yi, meaning the only GT characters who can withstand it are SS4 Gogeta and maybe EoGT Goku via assumptions.
San Xing Long (Eis Shenron) didn't have many feats or statements going for him, though his general similarity to Si, along with Goku not being able to dispose of him immediately would have me place him above all the other dragons aside from Si and Yi.