Who said Kali Yug is bad ?
Ved Vyasa himself said "Kali Sadhu:" - meaning Kali is great
Each Yug has its own methods of attaining Bhagavan. Kali is the easiest.
dhyayan krite yajan yajnais
tretayam dvapare arcayan
yad apnoti tad apnoti
kalau sankirtya kesavam
Whatever is achieved by dhyana in Satya-yuga,
antare chaiva samprApte kalidvAparayorabhUt | samantapa~nchake yuddhaM kurupANDavasenayoH || 9||
It was at this same Samantapañcaka that at the juncture of the dvApara yuga and the kali yuga the war between the armies of the Kurus and the Pāndavas was fought.
The relativity of dharma with respect to person is of primary importance to this question than the relativity of dharma with respect to time.
The simple answer may be that both Sudarsana and Rama are Jivan Mukthas from childhood i.e., self-realized at childhood itself.
Sudarsana is Jivan Muktha
Sudarsana also was, in appearance, as beautiful as the full ...
The four world Ages or Yugas is a Puranic invention. In the Vedic literature, there is no association of the world Ages with the purported four Yugas.
The names Kṛta, Tretā, Dvāpara and Kali has been derived from the Vedic literature and are associated with the game of dice. Again, and Again they appear in the Vedic literature in the context of the gambling....
Kalki is the Avatar of Kaliyuga. Though Lord Venkateswara is born to fulfill some of the promises he made in previous incarnations but he didnt kill any evil.
Logically Kalki will fight with Kali who is the head of Lust, gold etc..
currently kali is not visible to the physical world. so Kalki will be too.
Kalki will fight with Kali in a different dimension ...
In Kali-yuga Lord Siva appeared in the 8th Century as Sankaracharya.
In the Padma Purāṇa Vedic text it is stated that the Personality of Godhead ordered His Lordship Śiva to deviate the human race from Him (the Personality of Godhead).
The Personality of Godhead was to be so covered so that people would be encouraged to generate more and more population.