Create a number of mounts within sight. Every mount has a different cost that changes how many of each you can summon. The mounts will obey your and your allies commands. If they have attacks, roll separate initiative for the mounts.
Pony: AC 10; speed 50; HP 10; load 150 lbs; cost 5
Horse: AC 14; speed 60; HP 20; load 400 lbs; cost 10
Lizard: AC 12; speed 65; climb speed 30; HP 15; load 300 lbs; cost 15
Wolf: AC 16; speed 40; HP 25; load 250 lbs; AB +5; +4 initiative; claw 4d4 slashing; bite 2d10 piercing; cost 50
Giant Sea Turtle: AC 18; speed 20; swim speed 50; HP 40; load 500 lbs; cost 70
Riding Elephant: AC 20; speed 20; HP 120; load 1500 lbs; cost 100
War Elephant: AC 22; speed 20; HP 200; load 2500 lbs; AB +10; -2 initiative; stomp 4d8 bludgeoning; tusk 2d20; cost 150
Summoning energy at different spell slots:
4th 50
5th 70
6th 90
7th 110
8th 130
9th 150
* - (Horses hair, Elephant tusk, or similar depending on what you are trying to summon (DMs discretion).)