Use "Inferno Reckless Summon" before Synchro Summoning this card. It can help bring out Level 1-2 monsters that have (or can have) high ATK, especially on "The Calculator" Summoned through the effect of "Junk Synchron".
Use "Doppelwarrior" as a Synchro Material for this card, Chaining its effect to this card's effect so that this card will gain ATK from the "Doppel Tokens". Alternatively, "Doppelwarrior" can be used for another synchro summon, then use "Sonic Warrior" to Summon "Junk Warrior", allowing it to gain at least 1800 ATK.
Use the effects of the Level 2 monsters "Nimble Momonga" and/or "Giant Germ" beforehand, before Synchro Summoning this card.
Token Monsters are good monsters to control when this card is Synchro Summoned, as many of them are low-Level.
Use ATK-boosting Equip Spell Cards on your Level 1-2 monsters before Synchro Summoning this card. Powerful ones include "Mage Power" and "United We Stand".
In an all-Warrior-Type Deck (and most Extra Deck monsters), activate "The A. Forces" and/or "Solidarity" before Synchro Summoning this card, so it can gain extra ATK from your Level 1-2 monsters.
Use "The Golden Apples" before Synchro Summoning this card. The "Malus Token" will have potentially high ATK, aiding this monster's ATK boost.
"Junk Warrior" has good synergy with the "Ghostrick" family, as most of them are Level 1 or 2 with decent ATK. If one has enough Fiend and/or Spellcaster "Ghostricks" face-up, just Summon "Junk Synchron" to call forth one more from the Graveyard, Synchro Summon "Junk Warrior" and it'll gain a lot of power, becoming a powerful beatstick for the usually low-powered archetype.
Combo "Rush Warrior" and "Scrap Fist" with this card for a potential OTK. "Scrap Fist" will double any battle damage your opponent takes from attacks involving "Junk Warrior" during the turn its activated as well as grant it the ability of piercing battle damage and "Rush Warrior" will double the current ATK of "Junk Warrior". This can result in enough battle damage to win a duel if the ATK of "Junk Warrior" has been increased enough by its own effect.
Use "Graceful Charity" to draw 3 cards and discard "Quillbolt Hedgehog" and "Speed Warrior", then Normal Summon "Junk Synchron" and use the effect of "Quillbolt" and Special Summon it. Use the effect of "Junk Synchron" to Summon "Speed Warrior" and tune "Junk Synchron" and "Quillbolt". Lastly, Synchro Summon "Junk Warrior" and its ATK will become 3200.