These friendly primate-like aliens are found in Brinstar, through a secret path found by Power Bombing the bottom floor of the initial elevator room. The room they're in (referred to as “Hell” in concept artwork) can initially seem difficult to get out of. There is a vertical shaft to the right, where the Etecoons will jump on the walls back and forth until they get to the top.
The aliens are actually trying to teach Samus the Walljumping technique. If Samus continues to delay in the lower parts, the Etecoons will even jump back down and continue Walljumping to make sure Samus understands how to do it. If you reach the top and notice them jump down, you may also notice one jumping into a small right path on the wall, which leads to a pack of Power Bombs.
This long-legged bird alien is found in Brinstar, by Speed Boosting through the first pink hall, which causes the square blocks on the ground to crumble. The blocks will rematerialize, trapping Samus. Down here, though, the Dachora is found to the left. It runs right after a moment, then crouches and flashes, then jumps straight up. With this action, the creature is trying to show Samus how to perform a Shinespark, as that is the only way back up.
This turtle-like creature is found in a secret area in Maridia, with its children nearby. If you jump on its shell, it'll lift you up where you can grapple to an Energy Tank and a Missile Tank hidden in the right wall.
Though initially non-hostile, if the little ones are attacked, the Tatori will retaliate by spinning back-and-forth, which will cause damage if hit from the side.