Answer:
7119201225
Step-by-step explanation:
According to the question, Gengar becomes 75145118, means it is consdering A as 1, B as 2, C as 3 ............and Z as 26, and when a character repaets it does minus 2 like in the question G=7, E=5,N=14,again G which should be 7 but as its a repeated character we are doing -2 here i.e 5, and next character is A=1, R=18,
Similarly Gastly will be 7119201225