I think the problem is that elephants are specifically noted as being terrible at jumping in the introduction to the MM, under "Skills: Natural Tendencies". However, there is no reason why a goat the size of an elephant should be bad at it. I'd use the elephant stats, but remove a slam attack (no trunk), and swop Skill Focus (Listen) for Skill Focus (Jump). With its Strength of 30 (+10 to Jump checks) and Speed of 40 (+4 to Jump checks), it will have a final Jump modifier of +17. If that isn't high enough, you can give it a further racial bonus to Jump.
Don't forget that wearing armor can affect the Jump modifer both by slowing the creature and imposing an armor check penalty.
Here's a stat block for the final creature:
Battle Goat: CR 7; Huge Animal; HD 11d8+55; hp 104 hp; Init +0; Spd 40 ft.; AC 15, touch 8, flat-footed 15; Base Atk +8; Grp +26; Atk +16 melee (2d8+15, gore); Full Atk +16 melee (2d8+15, gore) and 2 stamps +11 melee (2d6+5); Space/Reach 15 ft./10 ft.; SA trample 2d8+15; SQ low-light vision, scent; AL N; Saves Fort +12, Ref +7, Will +6; Str 30, Dex 10, Con 21, Int 2, Wis 13, Cha 7.
Skills: Jump +17, Listen +9, Spot +10
Feats: Alertness, Endurance, Iron Will, Skill Focus (Jump)