Beast Boost can raise speed for a lot more than that, as long as you have their stats planned out correctly. Nihilego, Poipole, Naganadel, and Blacephalon can pretty easily manage it, and with enough distortion to the stat spread even Kartana, Celesteela, and Guzzlord can arrange to get speed as the highest stat (thus the one that gets the boost). Buzzwole can't do it unless its level was dropped all the way down to 14 (when it's never been made available that low), Xurkitree would need to be level 2, and of course Stakataka can't possibly hope to get speed the highest regardless of level, unless you're splicing raw stats with moves like Speed Swap.