Being better than a large amount of bad units isn't saying much. Xander as his competition is someone he can't compete with since xander's tankiness + lulzy 11mt sword with +4 def (better than innate aegis at least) makes him far better than leo as a whole. I mean I guess you can reclass leo to dark falcon to fix some things but that still leaves him frail as fuck (whereas dark knight is barely passable there). Ophelia's paralogue is still annoying to get to since your only good options for a good ophelia are really just elise/nyx, the latter of which is redundant and odin has a hard time getting support points with elise without blatant grinding or whatnot and even then he needs heavy favoritism.
Omega yato isn't good in all honesty. You still get the stat boosts by having it in your inventory, and its might isn't really stellar with forges or whatnot and waterwheel/braves are far better than it from an offensive standpoint and swords lack good range options since levin sword is pretty meh and kodachi just sucks. Master ninja is weak shit and debuffs aren't really that necessary when your units mostly one round ko (especially so in corrin's case), magic classes are still pretty meh. Idk what to say about birthright tbf since I just ryoma emblem'd it since he can solo the whole game once you get him. Spear master admittedly lacks guard/waterwheel but you're mostly just going for it on conquest for skills since rend heaven/quixotic are probably the most versatile skills in game. Rev final boss is a joke. Literally just an hp tank and can't really threaten your uits as a whole.
Wyvern lord is alright but definitely not a good end class since flying utility is offset by bow weakness and having a lackluster speed cap though that isn't much of an issue in revelation/birthright I suppose. Absolutely horrendous flaw in pvp though.
You can't really say Leo is worse than Xander when Leo hits Res and has an actual Res stat (Xander cannot tank Magic well at all). He comes ready to go at join time and only needs minimal investment to put in work (he caps Speed on average with just 1 Speedwing which you can easily spare), I would definitely say he is a solid unit.
Odin comes early enough to where he can be benched comfortably if you don't want to use him past unlocking Ophelia. The paralogue is still worth unlocking for the great loot.
Omega Yato is still nice for chewing through the final bosses faster (partial Dragonskin negation), though I guess it isn't required. 16 Mt is still great even with forging since you can only realistically forge +2 in a standard playthrough (maybe +3) and idt a +2 Steel Sword breaks 16 mt. You also sorely undervalue magic builds, tomes and magic weapons provide reliable 1-2 range and there are some great tomes out there (Horse Spirit, Lightning). CQ Corrin also particularly enjoys magic builds since Dragonstone is super nice early for tanking and Nohr Noble is worth staying in for its good skills.
I don't care about PvP at all lol.