Random scoring question

Short answer: yes
Long answer: it’s gonna take a lot of work to get there. Any red with a BST of 155 or higher can score that high with a high enough scoring build and very heavily merged. As an easy benchmark point, I’ll use a commonly 5*+10 Red in A!Tiki. If you give her aether steady breath QR and a high scoring C skill and seal, (note you don’t need a dual rally) she hits a 744 scoring mark, but only at +10. As the BST goes up it will get easier to hit that 742 mark but it will take time nonetheless.

Any hero with 155-159 BST can, but will have to have a legendary and DC(above 2200 sp total for skills). 160-164 BST must have at least 2100 in sp skills, above 165 must have at least 2000 sp in skills.

Heroes that sastify those conditions: Draug, Ayra, Fallen Celica, Tiki (Y), Mia, Legendary Ike, Soleil, Gray, Sigurd, Ryoma, Marth, Roy, Ike, Corrin (M), Alm, Chrom, Seliph, Lyn, Eirika, Exalted Chrom, Siegbert, Lucina, Elincia, Eliwood, Eldigan(must be +spd, -anything but res to put him at 155 bst), Brave Roy(must be +def, -anything but hp to put him at 155 bst)