I already had 1 Sea Monster, so a 2nd one was nice. As you can see by my list, these ones are still okay with my summoners. The rest don't give the full benefit.

Sea Monster is now 1/2 to get to Level 2
Naga Fire Wizard is now 2/3 to get to Level 3
Goblin Mech is now 3/7 to get to Level 4
Divine Sorceress is now 3/6 to get to Level 4