Не используйте suptitle для этого. используйте fig.text (x, y, "Text", args)
# -*- coding: utf-8 -*-
import matplotlib.pyplot as plt
fig = plt.figure()
fig.text(0,0, 'Some Text', color='red')
fig.text(0.2,0.95, 'superDuperCool:', fontsize=12, fontweight='bold')
fig.text(0.45,0.95,'9001', fontsize=14, fontweight='bold', color='green')
ax = fig.add_subplot(111)
fig.subplots_adjust(top=0.85)
ax.set_title('axes title')
ax.set_xlabel('xlabel')
ax.set_ylabel('ylabel')
ax.plot([2], [1], 'o')
ax.annotate('annotate', xy=(2, 1), xytext=(3, 4),
arrowprops=dict(facecolor='black', shrink=0.05))
ax.axis([0, 10, 0, 10])
plt.show()