Summons will be the summoner's level when summoned, no matter which level is in the stat.
(They might not level up when you level up in combat but that does not happen often enough to really matter. The next summon after your level-up will then have your new level.)

The only thing, you need to pick a character from root templates you want to use as a summon, possibly create a new one because you might want to give the summon different stats from what the existing templates have assigned.