General Gameplay Tips

• Most if not all opponents' levels are based off of your school's, which may suggest that keeping your school at a low level may ironically make the game easier.
• Battles are mostly against other schools, which have their own units. This gives each battle a predictable set of possible opponents, which will need to be gone over in a route of the game.
• Combo Attack 2 and 4 should be unlocked as soon as possible, which will make your units extremely powerful. Other innate abilities, like Indomitable Will are also useful. Affinity Attacks, status-effect attacks, etc. don't seem to be useful enough for a speedrun.
• Equipping an accessory that increases critical hit damage is useful, though one must watch out for enemies equipped with a critical defense accessory.
• There is usually a "best" set of equipment in each region. You are only restricted from equipping when the item is at a higher level than your school's rank. For amateur schools, you can only equip items level 5 or lower. For semi-pro the items must be level 10 or lower. At pro there are no level restrictions. Since for a speedrun, getting critical hits most if not all the time is necessary, your gladiators' accuracy levels can be disregarded, and you can just equip them with whatever weapon does the most damage in that region.
• After the first one or two regions are completed, money doesn't seem to be much of a hindrance.
• Equipping a secutor with the accessory that increases move-to-attack range will allow them to move to the flank of an enemy to do Surprise Attack. This is sold in the accessory shop in Imperia.
• Points Battles require a contradictory approach than normal battles. They are very easy to win since you will be doing much more critical hits than your opponents, along with playing smarter, so doing attacks that take a long time to perform will help the time go by. The timer only goes when performing the attack or when opponents are taking their turns. It does not go when you are choosing what to do. Attacks like Gungnir/Peltast Long Throws and other units' Running Attacks use one of the slowest meters in the game, and just allowing them to run all the way out take upwards of 15 seconds. An analysis of the length of each move will be useful for planning a speedrun.
• Rival Nations battles can be won by sending a powerful unit directly to the opponents statue. In Nordagh with Ursula's story, sending Urlan to do Combo Attack 2 will usually do the trick pretty easily.
• King of the Hill and Dominance battles are probably quicker to complete by killing all of your enemies rather than earning points by being on the hill or hotspots. They will likely require a different strategy than basic battles since the enemies will concentrate on the hill and hotspots.
• The awareness innate ability will protect you from secutors and bandits, so it's worth getting after unlocking Combo Attack 2 and 4.

RNG in Gladius

• Shops are influenced the most by RNG. Normal shops seem to have the same weapons in the store every time but the available affinity of the weapons can change. The accessory salesman has a completely random selection of items. Damage Reduction items are the best accessories you can get so it might be worth to save and reload at the beginning of the game to get at least one of these items for a gladiator that is often used. A Talisman for the channeler is also a nice accessory to get.
• The positioning of the barrels in barrel battles can vary a lot and sometimes makes it really hard to even win a battle if the battles are a lot closer to the opponents team. This is worth reentering the battle.
• Some opposing teams have a wide variety of gladiators and reentering can change the selected gladiators of the AI enough to make battles faster. Sometimes it's only the level and formation that changes, like Ursula's Yeti fight that she has to do alone.
• Every gladiator in the recruitment office has a certain porbability to appear in that office. Some gladiators are guaranteed to appear because they have a 100% probability. The guide by slartifer has a helpful list with all recruitable gladiators and their probabilty: Game Mechanics FAQ.