Additional to what vj1111 has said : Coulson without T2 is useless, beast and Ancient One are both good leaders already at T1, T2 only gives them a slight extra boost.
Uni for ancient one only changes his gender but t2 a1 is good as he gives 25%elemental damage and ignore dodge..
Coulson and beast are good for wbu @ t2 (their unis are NOT needed) for their useful passive support in WBU..
Other similarly available character are Shuri(t2 passive), warlock(similar to beast , skill 5 and tag Main DPS char) and She hulk at T1 for her mastery alone...
Valkyrie/Ghost panther are paywall characters with t2 passive similar to coul/shuri..