I tend to think Advance Wars was remarkably well balanced. It was designed to be a single player game so some strategies like rocket troops wasn't too bad. They were very slow however, which made them a really inefficient way to win.
Odd because I was just thinking that Advance Wars was one of the worst offenders for being unbalanced. Most scenarios give the AI anywhere from a huge to an enormous resource advantage, one that immediately disappears the instant you abuse the AI brain damage to run infantry over to their capital and completely own everything because the AI never thinks to defend its capital.
But also if you play with anywhere near balanced resources between the sides you will crush the AI. It's so dumb.
The crazy thing is that to get a good score (that coveted S rank) you have to abuse the absolute ineptitude of the AI to do a commando raid on its capital. The game designers balanced the game against abusing the AI stupidity. Strategy and tactics are mostly there to delay the AI and it's 50x production advantage while you rush an APC around the edge of the map.
I was never much for cheese when I played that game as a kid but I'm pretty sure I got S ranks on most things without it.
Advance Wars was a single player game (more or less). Fighting an overpowered foe and beating them with your brain was the whole appeal of a strategy game. Overcoming horrible odds was the point, both gameplay wise and narrative wise in pretty much every mission. It was super fun. The secret of strategy games is that they're much more fun this way. Focusing on multiplayer is what drained the RTS genre of its appeal.
I too think Advance Wars was really fun, and the AI was in fact smarter than say... Wargroove (Chucklefish did a good job with Wargroove too though, but were clearly leaning on the "resource heavy" approach moreso than Adv. Wars).
The "mech. infantry spam" almost made you C-rank (or worse) each map. Mech. Infantry was too slow to beat any mission. But if you wanted a reliable win-path (and didn't care about the time it took to win), Mech. Infantry spam was the way to go.
Adv. Wars "balanced" it out in their own way: not by nerfing units, but by simply encouraging the S-rank screen, taunting the player to beat the map faster (which meant building less-efficient, but faster, higher-cost units like tanks)
