>>56517970It's primarily speculation, but it's a reasonable assumption considering Terapagos was made a core component of Horizons' narrative and cast since the very first episode and its inherent ties to Lucius, his Pokemon and the promised land of Laqua.
Furthermore, the games and anime are more synced up than you think, because Terapagos in the anime only revealed its Terastal Form and the use of Tera Starstorm on same the day as Indigo Disk's release, no doubt to hype the Japanese kiddies up to get their hands on that power for themselves within SV.
As we approach what's looking like the buildup to narrative climax with Horizons, finally seeing more aspects of how Terapagos relates to Laqua such as its ability to nullify Laquium's effects on Pokemon, it's becoming apparent that Horizons is where Terapagos' story truly lies, and that its inclusion in Indigo Disk was simply to serve as a plot device for Kieran to strive for during the promised return to Area Zero.