1. Nine-Tails: The strongest of the nine Tailed Beasts in Naruto, controlled by Madara and Obito. Hashirama tamed it before turning it into Konoha's exclusive Tailed Beast using Mokuton.

2. Three Sages: Hashirama's Sage Mode is the most powerful. The three Great Sage locations are Myoboku Mountain, Ryuchi Cave, and Shikkotsu Forest, housing Gamamaru, Orochimaru's White Snake, and Katsuyu respectively. 

3. Gato: A powerful monster residing in the Box of Paradise in "Blood Prison" movie. Can dodge all attacks, even Gamabunta and the Eight-Tails. A potential summon for Hashirama. 

4. Ten-Tails: The strongest monster in the ninja world and the culmination of all Tailed Beasts. Typically tamed by a Ten-Tails Jinchuriki. If Hashirama could tame it, he would surpass the Six Paths Sage.

5. Outer Path: The vessel of the Ten-Tails with immense power, controlled by Madara, Nagato, and Obito. Choosing the Outer Path as a summon would give Hashirama full control over it.