Mother Gengar is actually the EASIER one to play. Both versions focus on swarming Gengar, the only difference being a single Nidoqueen who should be present asap in MG. With the addition of Nidoqueen, the Gengar player does NOT have to watch out for
-Any kind of Poison
-Crobat G sniping
-Spiritomb dropping
-Cresselia X
And the list goes on. So basically the single Queen makes the whole game easier and safer for Gengar.